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2010-04-23
Metal-insulator transition and the Pr$^{3+}$/Pr$^{4+}$ valence shift in (Pr$_{1-y}$Y$_{y}$)$_{0.7}$Ca$_{0.3}$CoO$_3$
The magnetic, electric and thermal properties of the ($Ln_{1-y}$Y$_{y}$)$_{0.7}$Ca$_{0.3}$CoO$_3$ perovskites ($Ln$~=~Pr, Nd) were investigated down to very low temperatures. The main attention was given to a peculiar metal-insulator transition, which is observed in the praseodymium based samples with $y=0.075$ and 0.1...
1004.4100v2
2010-07-07
The Chemical Evolution of the Monoceros Ring/Galactic Anticenter Stellar Structure
The origin of the Galactic Anticenter Stellar Structure (GASS) or "Monoceros ring" --- a low latitude overdensity at the edge of the Galactic disk spanning at least the second and third Galactic quadrants --- remains controversial. Models for the origin of GASS fall generally into scenarios where it is either a part (e...
1007.1056v1
2010-09-17
First-principles studies of Ce-doped RE2M2O7 (RE=Y,La;M=Ti,Zr,Hf): A class of non-scintillators
Lanthanum and yttrium compounds with composition RE2M2O7 (RE=Y, La; M = Ti, Zr, Hf) have high density and high Z and can be doped with Ce onto the La and Y sites. This makes these compounds good candidates for Ce activated scintillator gamma-ray detectors particularly for the hafnate systems which have a very high dens...
1009.3381v1
2010-12-05
The solar photospheric abundance of zirconium
Zirconium (Zr), together with strontium and yttrium, is an important element in the understanding of the Galactic nucleosynthesis. In fact, the triad Sr-Y-Zr constitutes the first peak of s-process elements. Despite its general relevance not many studies of the solar abundance of Zr were conducted. We derive the zircon...
1012.1038v1
2011-06-06
Protons in lattice confinement: Static pressure on the Y-substituted, hydrated BaZrO3 ceramic proton conductor decreases proton mobility
Yttrium substituted BaZrO3, with nominal composition BaZr0.9Y0.1O3, a ceramic proton conductor, was subject to impedance spectroscopy for temperatures 300 K < T < 715 K at mechanical pressures 1 GPa < p < 2 GPa. The activation energies Ea of bulk and grain boundary conductivity from two perovskites synthesized by solid...
1106.1091v1
2012-05-11
Novel multifunctional 90Y-labelled albumin magnetic microspheres for cancer therapy
We present in vitro and in vivo studies of yttrium-90 (90Y)-labelled human serum albumin magnetic microspheres (HSAMMS) as multifunctional agent for bimodal radionuclide-hyperthermia cancer therapy. The HSAMMS were produced using a modified emulsification-heat stabilization technique and contained 10-nm magnetite nanop...
1205.2440v1
2013-07-17
Temperature-driven Phase Transformation in Y_3Co: Neutron Scattering and First-principles Studies
Contrary to previous studies that identified the ground state crystal structure of the entire R_3Co series (R is a rare earth) as orthorhombic Pnma, we show that Y_3Co undergoes a structural phase transition at T_t=160K. Single crystal neutron diffraction data reveal that at T_t the trigonal prisms formed by a cobalt a...
1307.4736v1
2013-07-18
Numerical response of the magnetic permeability as a funcion of the frecuency of NiZn ferrites using Genetic Algorithm
The magnetic permeability of a ferrite is an important factor in designing devices such as inductors, transformers, and microwave absorbing materials among others. Due to this, it is advisable to study the magnetic permeability of a ferrite as a function of frequency. When an excitation that corresponds to a harmonic...
1307.5007v1
2013-08-12
Diamond Magnetometry of Superconducting Thin Films
In recent years diamond magnetometers based on the nitrogen-vacancy (NV) center have been of considerable interest for magnetometry applications at the nanoscale. An interesting application which is well suited for NV centers is the study of nanoscale magnetic phenomena in superconducting materials. We employ the magne...
1308.2689v3
2014-01-22
Dzyaloshinskii-Moriya nature of ferroelectric ordering in magnetoelectric Gd$_{1-x}$Y$_{x}$MnO$_{3}$ system
This work reports on magnetic, dielectric, thermodynamic and magnetoelectric properties of Gd$_{1-x}$Y$_{x}$MnO$_{3}$, with 0 \leq x \leq 0.4, with emphasis on the (x, T) phase diagram, towards unraveling the role of the driving mechanisms in stabilizing both magnetic and ferroelectric orderings. The (x, T) phase diagr...
1401.5718v2
2014-01-29
Nucleosynthesis in helium-enriched asymptotic giant branch models: Implications for Heavy Element Enrichment in Omega Centauri
We investigate the effect of helium enrichment on the evolution and nucleosynthesis of low-mass asymptotic giant branch (AGB) stars of 1.7Msun and 2.36Msun with a metallicity of Z=0.0006 ([Fe/H] = -1.4). We calculate evolutionary sequences with the primordial helium abundance (Y = 0.24) and with helium-enriched composi...
1401.7479v1
2014-03-19
Pt-based nanowire networks with enhanced oxygen-reduction activity
Pt-Al and Pt-Y-Al thin film electrodes on yttria-stabilised zirconia electrolytes were prepared by dealloying of co-sputtered Pt-Al or Pt-Y-Al films. The selective dissolution of Al from the Pt-alloy compound causes the formation of a highly porous nanowire network with a mean branch thickness below 25 nm and a pore in...
1403.4665v4
2014-05-23
Proof-of-principle of a new geometry for sampling calorimetry using inorganic scintillator plates
A novel geometry for a sampling calorimeter employing inorganic scintillators as an active medium is presented. To overcome the mechanical challenges of construction, an innovative light collection geometry has been pioneered, that minimises the complexity of construction. First test results are presented, demonstratin...
1405.6202v1
2014-07-29
Discovery of extremely lead-rich subdwarfs: does heavy metal signal the formation of subdwarf B stars?
Hot subdwarfs represent a group of low-mass helium-burning stars formed through binary-star interactions and include some of the most chemically-peculiar stars in the Galaxy. Stellar evolution theory suggests that they should have helium-rich atmospheres but, because radiation causes hydrogen to diffuse upwards, a majo...
1407.7668v1
2015-04-28
High-precision abundances of elements in solar twin stars: Trends with stellar age and elemental condensation temperature
HARPS spectra with S/N > 600 for 21 solar twin stars are used to determine very precise (sigma ~ 0.01 dex) differential abundances of C, O, Na, Mg, Al, Si, S, Ca, Ti, Cr, Fe, Ni, Zn, and Y in order to see how well [X/Fe] is correlated with elemental condensation temperature, Tc. In addition, precise (sigma < 0.8 Gyr) s...
1504.07598v1
2015-06-18
Short intense ion pulses for materials and warm dense matter research
We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment-II at Lawrence Berkeley National Laboratory, by generating beam spots size with radius r < 1 mm within 2 ns FWHM and approximately 10^10 ions/pulse. To enable the short pulse durations and mm-scale focal...
1506.05839v1
2015-09-15
Measurement of time resolution of the Mu2e LYSO calorimeter prototype
In this paper we present the time resolution measurements of the Lutetium-Yttrium Oxyorthosilicate (LYSO) calorimeter prototype for the Mu2e experiment. The measurements have been performed using the $e^-$ beam of the Beam Test Facility (BTF) in Frascati, Italy in the energy range from 100 to 400 MeV. The calorimeter p...
1509.04468v2
2015-11-16
The evolved pulsating CEMP star HD112869
Radial velocity measurements, $BVR_C$ photometry, and high-resolution spectroscopy in the wavelength region from blue to near infrared are employed in order to clarify the evolutionary status of the carbon-enhanced metal-poor star HD112869 with unique ratio of carbon isotopes in the atmosphere. An LTE abundance analysi...
1511.04953v2
2016-02-18
Hole-doping-induced melting of spin-state ordering in PrBaCo2O5.5+x
The layered perovskite cobaltite RBaCo$_2$O$_{5.5}$ (R: rare-earth elements or Yttrium) exhibits an abrupt temperature-induced metal$-$insulator transition (MIT) and has been attributed to spin-state ordering (SSO) of Co$^{3+}$ ions. Here we investigated the hole doping member of PrBaCo$_2$O$_{5.5+x}$ ($0 \le x \le 0.2...
1602.05687v2
2016-03-22
Polaronic contributions to oxidation and hole conductivity in acceptor-doped BaZrO$_3$
Acceptor-doped perovskite oxides like BaZrO$_3$ are showing great potential as materials for renewable energy technologies where hydrogen acts an energy carrier, such as solid oxide fuel cells and hydrogen separation membranes. While ionic transport in these materials has been investigated intensively, the electronic c...
1603.06728v2
2017-01-20
Ultrafast X-ray Diffraction Thermometry Measures the Influence of Spin Excitations on the Heat Transport through nanolayers
We investigate the heat transport through a rare earth multilayer system composed of Yttrium (Y), Dysprosium (Dy) and Niobium (Nb) by ultrafast X-ray diffraction. This is an example of a complex heat flow problem on the nanoscale, where several different quasi-particles carry the heat. The Bragg peak positions of each ...
1701.05918v1
2017-10-24
Hyperfine interactions of $\text{Er}^{3+}$ ions in $\text{Y}_2\text{SiO}_{5}$: electron paramagnetic resonance in a tunable microwave cavity
The hyperfine structure of the ground state of erbium doped yttrium orthosilicate is analyzed with the use of electron paramagnetic resonance experiments in a tunable microwave resonator. This work was prompted by the disagreement between the measurements made in zero magnetic field [Phys. Rev. B, 94, 075117, (2016)] a...
1710.09014v2
2017-11-06
A Raman-Heterodyne Study of the Hyperfine Interaction of the Optically-Excited State $^5$D$_0$ of Eu$^{3+}$:Y$_2$SiO$_5$
The spin coherence time of $^{151}$Eu$^{3+}$ which substitutes the yttrium at site 1 in Y$_2$SiO$_5$ crystal has been extended to 6 hours in a recent work [\textit{Nature} \textbf{517}, 177 (2015)]. To make this long-lived spin coherence useful for optical quantum memory applications, we experimentally characterize the...
1711.01814v2
2017-11-16
Anisotropy and phonon modes from analysis of the dielectric function tensor and inverse dielectric function tensor of monoclinic yttrium orthosilicate
We determine the frequency dependence of the four independent Cartesian tensor elements of the dielectric function for monoclinic symmetry Y$_2$SiO$_5$ using generalized spectroscopic ellipsometry from 40-1200 cm$^{-1}$. Three different crystal cuts, each perpendicular to a principle axis, are investigated. We apply ou...
1711.06336v1
2017-12-29
Origins and dissociation of pyramidal <c + a> dislocations in magnesium and its alloys
Alloying magnesium (Mg) with rare earth elements such as yttrium (Y) has been reported to activate the pyramidal <c + a> slip systems and improve the plasticity of Mg at room temperature. However, the origins of such dislocations and their dissociation mechanisms remain poorly understood. Here, we systematically invest...
1712.10098v1
2018-01-10
Study of a Prototype VP-PET Imaging System Based on highly Pixelated CdZnTe Detectors
We are investigating a prototype virtual pinhole positron emission tomography (VP-PET) system for small animal imaging applications. The PET detector modules were made up of 1.3 mm lutetium-yttrium oxyorthosilicate (LYSO) arrays, and the insert detectors consists of 0.6 mm pixelated Cadmium Zinc Telluride (CdZnTe). To ...
1801.03225v1
2018-01-11
Nano-machining, surface analysis and emittance measurements of a copper photocathode at SPARC_LAB
R\&D activity on Cu photocathodes is under development at the SPARC\_LAB test facility to fully characterize each stage of the photocathode "life" and to have a complete overview of the photoemission properties in high brightness photo-injectors. The nano(n)-machining process presented here consists in diamond milling,...
1801.03823v1
2018-02-17
Controlling rare-earth ions in a nanophotonic resonator using the ac Stark shift
On-chip nanophotonic cavities will advance quantum information science and measurement because they enable efficient interaction between photons and long-lived solid-state spins, such as those associated with rare-earth ions in crystals. The enhanced photon-ion interaction creates new opportunities for all-optical cont...
1802.06172v1
2018-03-05
Widefield imaging of superconductor vortices with electron spins in diamond
Understanding the mechanisms behind high-$T_{c}$ Type-II superconductors (SC) is still an open task in condensed matter physics. One way to gain further insight into the microscopic mechanisms leading to superconductivity is to study the magnetic properties of the SC in detail, for example by studying the properties of...
1803.01957v1
2018-08-22
Evidence against anomalous compositions for giants in the Galactic Nuclear Star Cluster
Very strong Sc I lines have been found recently in cool M giants in the Nuclear Star Cluster in the Galactic Center. Interpreting these as anomalously high scandium abundances in the Galactic Center would imply a unique enhancement signature and chemical evolution history for nuclear star clusters, and a potential test...
1808.07489v1
2018-11-21
Position Sensitive Alpha Detector for an Associate Particle Imaging System
Associated Particle Imaging (API) is a nuclear technique that allows for the nondestructive determination of 3D isotopic distributions. The technique is based on the detection of the alpha particles associated with the neutron emitted in the deuterium-tritium (DT) fusion reaction, which provides information regarding t...
1811.08591v1
2019-02-12
High Quality Factor High-Temperature Superconducting Microwave Cavity Development for the Dark Matter Axion Search in a Strong Magnetic Field
We demonstrate a superconducting (SC) microwave (mw) cavity that can accelerate the dark matter search by maintaining superconductivity in a high DC magnetic field. We used high-temperature superconductor (HTSC) yttrium barium copper oxide (YBCO) with a phase transition temperature of 90K to prevent SC failure by the m...
1902.04551v3
2019-03-04
Ionization-density-dependent Scintillation Pulse Shape and Mechanism of Luminescence Quenching in LaBr3:Ce
Pulse-shape discrimination (PSD) is usually achieved using the different fast and slow decay components of inorganic scintillators, such as BaF2, CsI:Tl, etc. However, LaBr3:Ce is considered to not possess different components at room temperature, but has been proved to have the capability of discriminating {\gamma} an...
1903.01452v3
2020-01-26
The Spectral and Magnetic Properties of Er$^{3+}$ and Yb$^{3+}$ Ions in Y$_{2}$Ti$_{2}$O$_{7}$ Crystals with a Pyrochlore Structure
Cubic Y$_{2}$Ti$_{2}$O$_{7}$ single crystals doped with Er$^{3+}$ and Yb$^{3+}$ ions have been studied by the methods of electron spin resonance (ESR) and selective laser spectroscopy. ESR spectra exhibit signals from rare-earth ions that substitute for yttrium ions in sites with local trigonal symmetry. The $g$ tensor...
2001.09447v1
2020-02-20
Reliable coherent optical memory based on a laser-written waveguide
$\mathrm {^{151}Eu^{3+}}$-doped yttrium silicate ($\mathrm {^{151}Eu^{3+}:Y_2SiO_5}$ ) crystal is a unique material that possesses hyperfine states with coherence time up to 6 h. Many efforts have been devoted to the development of this material as optical quantum memories based on the bulk crystals, but integrable str...
2002.08780v1
2020-02-21
Sensing individual nuclear spins with a single rare-earth electron spin
Rare-earth related electron spins in crystalline hosts are unique material systems, as they can potentially provide a direct interface between telecom band photons and long-lived spin quantum bits. Specifically, their optically accessible electron spins in solids interacting with nuclear spins in their environment are ...
2002.09357v2
2020-04-06
Successful production of Solution Blow Spun YBCO+Ag complex ceramics
YBCO fabrics composed of nanowires, produced by solution blow spinning (SBS) are so brittle that the Lorentz force produced by induced currents can be strong enough to damage them. On the other hand, it is known that silver addition improves the mechanical and flux pinning properties of ceramic superconductors. Thus, i...
2004.07287v2
2020-04-15
Experimental observation of magnetic dimers in diluted Yb:YAlO$_3$
We present a comprehensive experimental investigation of Yb magnetic dimers in Yb$_{0.04}$Y$_{0.96}$AlO$_3$, an Yb-doped Yttrium Aluminum Perovskite (YAP) YAlO$_3$ by means of specific heat, magnetization and high-resolution inelastic neutron scattering (INS) measurements. In our sample, the Yb ions are randomly distri...
2004.07325v1
2020-04-28
Al-dependent electronic and magnetic properties of YCrO$_3$ with magnetocaloric application: an ab-initio and Monte-Carlo approach
In this paper, a theoretical journey from electronic to magneto-caloric effect has been shown through the magnetic properties of aluminium induced yttrium chromate. The ground state electronic band structure and density of states have been studied using first principle calculations under GGA+U schemes. From the energy ...
2004.13456v2
2020-05-21
Local distortions and dynamics in hydrated Y-doped BaZrO$_3$
Y-doped BaZrO$_3$ is a promising proton conductor for intermediate temperature solid oxide fuel cells. In this work, a combination of static DFT calculations and DFT based molecular dynamics (DFT-MD) was used to study proton conduction in such a material. Geometry optimisations of 100 structures with a 12.5% dopant con...
2005.10877v1
2020-09-14
An all-digital associated particle imaging system for the 3D determination of isotopic distributions
Associated particle imaging (API) is a non-destructive nuclear technique for the 3D determination of isotopic distributions. By detecting the alpha particle associated with the emitted neutron in the deuterium-tritium fusion reaction with a position- and time-resolving detector, the direction of the 14.1 MeV neutron an...
2009.06768v2
2020-11-15
A single-projection three-dimensional reconstruction algorithm for scanning transmission electron microscopy data
Increasing interest in three-dimensional nanostructures adds impetus to electron microscopy techniques capable of imaging at or below the nanoscale in three dimensions. We present a reconstruction algorithm that takes as input a focal series of four-dimensional scanning transmission electron microscopy (4D-STEM) data. ...
2011.07652v2
2020-12-09
Kinetically-stabilized Ferroelectricity in Bulk Singlecrystalline HfO2:Y without Wake-up Effects
HfO2, a simple binary oxide, holds ultra-scalable ferroelectricity integrable into silicon technology. Polar orthorhombic (Pbc21) form in ultra-thin-films ascribes as the plausible root-cause of the astonishing ferroelectricity, which has thought not attainable in bulk crystals. Though, perplexities remain primarily du...
2012.05289v1
2021-02-08
Improvement of reversible H storage capacity by fine tuning of the composition in the pseudo-binary systems A2-xLaxNi7 (A = Gd, Sm, Y, Mg)
A2B7 compounds (A = rare earth or Mg, B = transition metal) are widely studied as active materials for negative electrode in Ni-MH batteries. By playing on the substitution rate of both A and B elements, it is possible to prepare various compositions. This strategy will help to improve the properties, for example get a...
2102.04161v1
2021-03-06
Spectroscopic Evidence for the Superconductivity of Elemental Metal Y under Pressure
Very high applied pressure induces superconductivity with the transition temperature ($T_c$) exceeding 19 K in elemental yttrium, but relatively little is known about the nature of that superconductivity. From point-contact spectroscopy (PCS) measurements in a diamond anvil cell (DAC), a strong enhancement in the diffe...
2103.04070v3
2021-03-18
An antisite defect mechanism for room temperature ferroelectricity in orthoferrites
Single-phase multiferroic materials that allow the coexistence of ferroelectric and magnetic ordering above room temperature are highly desirable, motivating an ongoing search for mechanisms for unconventional ferroelectricity in magnetic oxides. Here, we report an antisite defect mechanism for room temperature ferroel...
2103.10338v1
2021-06-08
Superconducting microresonators for electron spin resonance, the good, the bad, and the future
The field of electron spin resonance is in constant need to improve its capabilities. Among other things, this means having better resonators which would provide improved spin sensitivity, as well as enable larger microwave magnetic field power conversion factors. Surface micro resonators, made of small metallic patche...
2106.04163v2
2021-08-29
Nuclear spin-wave quantum register for a solid state qubit
Solid-state nuclear spins surrounding individual, optically addressable qubits provide a crucial resource for quantum networks, computation and simulation. While hosts with sparse nuclear spin baths are typically chosen to mitigate qubit decoherence, developing coherent quantum systems in nuclear spin-rich hosts enable...
2108.12723v1
2021-09-11
Dzyaloshinskii interaction and exchange-relativistic effects in orthoferrites
We present an overview of the microscopic theory of the Dzyaloshinskii-Moriya (DM) coupling and related exchange-relativistic effects such as exchange anisotropy, electron-nuclear antisymmetric supertransferred hyperfine interactions, antisymmetric magnetogyrotropic effects, and antisymmetric magnetoelectric coupling i...
2109.05326v1
2021-11-20
Trivalent ion overcharging on electrified graphene
The structure of the electrical double layer (EDL) formed near graphene in aqueous environments strongly impacts its performance for a plethora of applications, including capacitive deionization. In particular, adsorption and organization of multivalent counterions near the graphene interface can promote nonclassical b...
2111.10516v2
2021-12-09
Comparative studies of hydrogen dissolution and release behavior in zirconate oxides by TDS and TMAP4 analysis
Proton-conducting oxides are potential materials for electrochemical devices such as fuel cells, hydrogen pumps, hydrogen sensors, and the tritium purification and recovery system in nuclear fusion reactors. The hydrogen concentration in oxide materials is important, but its precise measurement is difficult. In this st...
2112.04649v1
2022-07-06
Robust millisecond coherence times of erbium electron spins
Erbium-doped solids are prime candidates for optical quantum communication networks due to erbium's telecom C-band emission. A long-lived electron spin of erbium with millisecond coherence time is highly desirable for establishing entanglement between adjacent quantum repeater nodes while long-term storage of the entan...
2207.02708v1
2022-09-15
Yttrium incorporation in Cr2AlC: On the metastable phase formation and decomposition of (Cr,Y)2AlC MAX phase thin films
Herein we report on the synthesis of a metastable (Cr,Y)2AlC MAX phase solid solution by co-sputtering from a composite Cr-Al-C and elemental Y target, at room temperature, followed by annealing. While direct high-temperature synthesis resulted in multiphase films, as evidenced by X-ray diffraction analyses, room tempe...
2209.07119v1
2022-11-29
Comparative Analysis of the Electronic Energy Structure of Nanocrystalline Polymorphs of Y2O3 Thin Layers: Theory and Experiments
The results of fabrication and characterization of atomic structure of nanocrystalline thin layers of Y2O3 in cubic and monoclinic phases is reported. Experimental data demonstrate crystalline ordering in nanocrystalline films with average grain size of ~10-14 nm both for cubic and monoclinic studied structures. Densit...
2211.16004v1
2023-01-18
Stripe Symmetry of Short-range Charge Density Waves in Cuprate Superconductors
The omnipresence of charge density waves (CDWs) across almost all cuprate families underpins a common organizing principle. However, a longstanding debate of whether its spatial symmetry is stripe or checkerboard remains unresolved. While CDWs in lanthanum- and yttrium-based cuprates possess a stripe symmetry, distingu...
2301.07637v1
2023-04-28
Phantom study for 90Y post-treatment dosimetry with a long axial field-of-view PET/CT
Purpose: The physical properties of yttrium-90 (90Y) allow for imaging with positron emission tomography/computed tomography (PET/CT). The increased sensitivity of long axial field-of-view (LAFOV) PET/CT scanners possibly allows to overcome the small branching ratio for positron production from 90Y decays and to improv...
2304.14797v2
2023-08-29
KilonovAE: Exploring Kilonova Spectral Features with Autoencoders
Kilonovae are likely a key site of heavy r-process element production in the Universe, and their optical/infrared spectra contain insights into both the properties of the ejecta and the conditions of the r-process. However, the event GW170817/AT2017gfo is the only kilonova so far with well-observed spectra. To understa...
2308.15657v2
2023-09-11
Topological phase transition and tunable surface states in YBi
A unique co-existence of extremely large magnetoresistance (XMR) and topological characteristics in non-magnetic rare-earth monopnictides stimulating intensive research on these materials. Yttrium monobismuthide (YBi) has been reported to exhibit XMR up to 105% but its Topological properties still need clarification. H...
2309.05553v1
2023-12-12
Origin of correlated diffuse scattering in the hexagonal manganites
We use a combination of first-principles density functional calculations and spin-dynamics simulations to explain the unusual diffuse inelastic neutron scattering in the hexagonal multiferroic yttrium manganite, YMnO$_3$. Using symmetry considerations, we construct a model spin Hamiltonian with parameters derived from ...
2312.07449v2
2023-12-21
The Numerical Equivalence of Diabatic and Adiabatic Representations in Diatomic Molecules
The (stationary) Schr\"{o}dinger equation for atomistic systems is solved using the adiabatic potential energy curves (PECs) and the associated adiabatic approximation. Despite being very simplistic, this approach is very powerful and used in nearly all practical applications. In cases when interactions between electro...
2312.13895v1
2024-01-24
3D NLTE modelling of Y and Eu. Centre-to-limb variation and solar abundances
Context. Abundances of s- and r-process elements in Sun-like stars constrain nucleosynthesis in extreme astrophysical events, such as compact binary mergers and explosions of highly magnetised rapidly rotating massive stars. Aims. We measure solar abundances of yttrium (Y) and europium (Eu) using 3D non-local thermal...
2401.13450v1
2024-01-26
Engineering strong magnetoelectricity using a hexagonal 2D material on electron-doped hexagonal LuFeO$_3$
Cubic perovskite-structure ABO$_3$ and A$_{1-x}$A$^{\prime}$$_x$BO$_3$-type oxides have been investigated extensively while their hexagonal-structure versions have received minimal attention, even though they are multiferroic and can form heterostructures with the manifold hexagonal two-dimensional materials. Hexagonal...
2401.15053v1
2006-12-14
On Site Raman Analysis of Iznik Pottery Glazes and Pigments
On site Raman analyses were performed at the Mus\'{e}e national de C\'{e}ramique, S\`{e}vres, France, on rare Iznik (former Nicaea) pottery produced from ~1480 to ~1620. A comparison is made with a series of shards. The town of production of these potteries was highly disputed in the 80's and many questions still remai...
0612375v1
2006-01-24
Trapping atoms on a transparent permanent-magnet atom chip
We describe experiments on trapping of atoms in microscopic magneto-optical traps on an optically transparent permanent-magnet atom chip. The chip is made of magnetically hard ferrite-garnet material deposited on a dielectric substrate. The confining magnetic fields are produced by miniature magnetized patterns recorde...
0601163v2
2008-10-14
Field induced magnetic order in the frustrated magnet Gadolinium Gallium Garnet
Gd3Ga5O12, (GGG), has an extraordinary magnetic phase diagram, where no long range order is found down to 25 mK despite \Theta_CW \approx 2 K. However, long range order is induced by an applied field of around 1 T. Motivated by recent theoretical developments and the experimental results for a closely related hyperkago...
0810.2410v1
2010-08-06
Photon Self-Induced Spin to Orbital Conversion in TGG crystal at high laser power
In this paper, we present experimental evidence of a newly discovered third-order nonlinear optical process Self-Induced Spin-to-Orbital Conversion (SISTOC) of the photon angular momentum. This effect is the physical mechanism at the origin of the depolarization of very intense laser beams propagating in isotropic mate...
1008.1283v1
2011-08-03
Optimizing large parameter sets in variational quantum Monte Carlo
We present a technique for optimizing hundreds of thousands of variational parameters in variational quantum Monte Carlo. By introducing iterative Krylov subspace solvers and by multiplying by the Hamiltonian and overlap matrices as they are sampled, we remove the need to construct and store these matrices and thus byp...
1108.0900v1
2012-03-08
Truncated Configuration Interaction expansions as solvers for correlated quantum impurity models and dynamical mean field theory
The development of polynomial cost solvers for correlated quantum impurity models, with controllable errors, is a central challenge in quantum many-body physics, where these models find applications ranging from nano-science to the dynamical mean-field theory (DMFT). Here we describe how configuration interaction (CI) ...
1203.1914v1
2013-02-10
Efficient Tree Tensor Network States (TTNS) for Quantum Chemistry: Generalizations of the Density Matrix Renormalization Group Algorithm
We investigate tree tensor network states for quantum chemistry. Tree tensor network states represent one of the simplest generalizations of matrix product states and the density matrix renormalization group. While matrix product states encode a one-dimensional entanglement structure, tree tensor network states encode ...
1302.2298v2
2013-05-08
The Thouless theorem for matrix product states and subsequent post-density matrix renormalization group methods
The similarities between Hartree-Fock (HF) theory and the density-matrix renormalization group (DMRG) are explored. Both methods can be formulated as the variational optimization of a wave-function ansatz. Linearization of the time-dependent variational principle near a variational minimum allows to derive the random p...
1305.1761v3
2013-09-09
Spectral functions of strongly correlated extended systems via an exact quantum embedding
Density matrix embedding theory (DMET) [Phys. Rev. Lett., 109, 186404 (2012)], introduced a new approach to quantum cluster embedding methods, whereby the mapping of strongly correlated bulk problems to an impurity with finite set of bath states was rigorously formulated to exactly reproduce the entanglement of the gro...
1309.2320v2
2014-03-12
Projector quantum Monte Carlo with matrix product states
We marry tensor network states (TNS) and projector quantum Monte Carlo (PMC) to overcome the high computational scaling of TNS and the sign problem of PMC. Using TNS as trial wavefunctions provides a route to systematically improve the sign structure and to eliminate the bias in fixed-node and constrained-path PMC. As ...
1403.3125v2
2014-08-21
A spin-adapted Density Matrix Renormalization Group algorithm for quantum chemistry
We extend the spin-adapted density matrix renormalization group (DMRG) algorithm of McCulloch and Gulacsi [Europhys. Lett.57, 852 (2002)] to quantum chemical Hamiltonians. This involves two key modifications to the non-spin-adapted DMRG algorithm: the use of a quasi-density matrix to ensure that the renormalised DMRG s...
1408.5039v1
2014-08-21
Spectroscopic accuracy directly from quantum chemistry: application to ground and excited states of beryllium dimer
We combine explicit correlation via the canonical transcorrelation approach with the density matrix renormalization group and initiator full configuration interaction quantum Monte Carlo methods to compute a near-exact beryllium dimer curve, {\it without} the use of composite methods. In particular, our direct density ...
1408.5090v1
2015-12-16
Hilbert space renormalization for the many-electron problem
Renormalization is a powerful concept in the many-body problem. Inspired by the highly successful density matrix renormalization group (DMRG) algorithm, and the quantum chemical graphical representation of configuration space, we introduce a new theoretical tool: Hilbert space renormalization, to describe many-electron...
1512.05218v1
2016-03-21
From plane waves to local Gaussians for the simulation of correlated periodic systems
We present a simple, robust and black-box approach to the implementation and use of local, periodic, atom-centered Gaussian basis functions within a plane wave code, in a computationally efficient manner. The procedure outlined is based on the representation of the Gaussians within a finite bandwidth by their underlyin...
1603.06457v3
2016-04-05
Simulation of White Light Generation and Near Light Bullets Using a Novel Numerical Technique
An accurate and efficient simulation has been devised, employing a new numerical technique to simulate the derivative generalised non-linear Schr\"odinger equation in all three spatial dimensions and time. The simulation models all pertinent effects such as self-steepening and plasma for the non-linear propagation of u...
1604.01140v3
2016-05-09
Matrix Product Operators, Matrix Product States, and ab initio Density Matrix Renormalization Group algorithms
Current descriptions of the ab initio DMRG algorithm use two superficially different languages: an older language of the renormalization group and renormalized operators, and a more recent language of matrix product states and matrix product operators. The same algorithm can appear dramatically different when written i...
1605.02611v2
2016-07-05
Transport and selective chaining of bidisperse particles in a travelling wave potential
We combine experiments, theory and numerical simulation to investigate the dynamics of a binary suspension of paramagnetic colloidal particles dispersed in water and transported above a stripe patterned magnetic garnet film. The substrate generates a one-dimensional periodic energy landscape above its surface. The appl...
1607.01131v1
2016-09-24
A real-time extension of density matrix embedding theory for non-equilibrium electron dynamics
We introduce real-time density matrix embedding theory (DMET), a dynamical quantum embedding theory for computing non-equilibrium electron dynamics in strongly correlated systems. As in the previously developed static DMET, real-time DMET partitions the system into an impurity corresponding to the region of interest co...
1609.07678v2
2016-10-07
Polarizers, optical bridges and Sagnac interferometers for nanoradian polarization rotation measurements
The ability to measure nanoradian polarization rotations, $\theta_F$, in the photon shot noise limit is investigated for partially crossed polarizers (PCP), a static Sagnac interferometer and an optical bridge, each of which can in principal be used in this limit with near equivalent figures-of-merit (FOM). In practice...
1610.02297v3
2016-12-08
Quantum embedding theories
In complex systems, it is often the case that the region of interest forms only one part of a much larger system. The idea of joining two different quantum simulations - a high level calculation on the active region of interest, and a low level calculation on its environment - formally defines a quantum embedding. Whil...
1612.02576v2
2017-01-18
Excitation of magnon accumulation by laser clocking as a source of long-range spin waves in transparent magnetic films
Optical tools are of great promise for generation of spin waves due to the possibility to manipulate on ultrashort time scales and to provide local excitation. However, a single laser pulse can inject spin waves only with a broad frequency spectrum, resulting in a short propagation distance and low amplitude. Here we e...
1701.05109v1
2017-01-26
Automated construction of molecular active spaces from atomic valence orbitals
We introduce the atomic valence active space (AVAS), a simple and well-defined automated technique for constructing active orbital spaces for use in multi-configuration and multireference (MR) electronic structure calculations. Concretely, the technique constructs active molecular orbitals capable of describing all rel...
1701.07862v2
2017-05-01
Towards the solution of the many-electron problem in real materials: equation of state of the hydrogen chain with state-of-the-art many-body methods
We present numerical results for the equation of state of an infinite chain of hydrogen atoms. A variety of modern many-body methods are employed, with exhaustive cross-checks and validation. Approaches for reaching the continuous space limit and the thermodynamic limit are investigated, proposed, and tested. The detai...
1705.01608v2
2017-05-31
Low Depth Quantum Simulation of Electronic Structure
Quantum simulation of the electronic structure problem is one of the most researched applications of quantum computing. The majority of quantum algorithms for this problem encode the wavefunction using $N$ Gaussian orbitals, leading to Hamiltonians with ${\cal O}(N^4)$ second-quantized terms. We avoid this overhead and...
1706.00023v3
2017-12-19
Hole self-trapping in the Y3Al5O12 and Lu3Al5O12 garnet crystals
The processes of hole localization in the Y3Al5O12 and Lu3Al5O12 single crystals were investigated by electron paramagnetic resonance (EPR) and thermally stimulated luminescence (TSL). It was found that holes created by x-ray irradiation at 77 K are predominantly self-trapped at regular oxygen ions forming O- hole cent...
1712.06928v1
2018-03-19
A Perturbative Density Matrix Renormalization Group Algorithm for Large Active Spaces
We describe a low cost alternative to the standard variational DMRG (density matrix renormalization group) algorithm that is analogous to the combination of selected configuration interaction plus perturbation theory (SCI+PT). We denote the resulting method p-DMRG (perturbative DMRG) to distinguish it from the standard...
1803.07150v2
2018-05-02
Pseudo-Goldstone gaps and order-by-quantum-disorder in frustrated magnets
In systems with competing interactions, continuous degeneracies can appear which are accidental, in that they are not related to any symmetry of the Hamiltonian. Accordingly, the pseudo-Goldstone modes associated with these degeneracies are also unprotected. Indeed, through a process known as "order-by-quantum-disorder...
1805.00947v2
2018-12-12
Potential jumps at transport bottlenecks cause instability of nominally ionic solid electrolytes in electrochemical cells
Normal operations of electrochemical devices such as solid oxide fuel cells (SOFC), solid oxide electrolyzer cells (SOEC) and lithium ion batteries (LIB) sometimes fail because of unexpected formation of internal phases. These phases include oxygen bubbles at grain boundaries inside the zirconia electrolyte of SOEC, is...
1812.05187v5
2019-01-23
Determining eigenstates and thermal states on a quantum computer using quantum imaginary time evolution
The accurate computation of Hamiltonian ground, excited, and thermal states on quantum computers stands to impact many problems in the physical and computer sciences, from quantum simulation to machine learning. Given the challenges posed in constructing large-scale quantum computers, these tasks should be carried out ...
1901.07653v3
2019-02-21
Learning representations of irregular particle-detector geometry with distance-weighted graph networks
We explore the use of graph networks to deal with irregular-geometry detectors in the context of particle reconstruction. Thanks to their representation-learning capabilities, graph networks can exploit the full detector granularity, while natively managing the event sparsity and arbitrarily complex detector geometries...
1902.07987v2
2019-04-17
Graphene Induced Large Shift of Surface Plasmon Resonances of Gold Films: Effective Medium Theory for Atomically Thin Materials
Despite successful modeling of graphene as a 0.34-nm thick optical film synthesized by exfoliation or chemical vapor deposition (CVD), graphene induced shift of surface plasmon resonance (SPR) of gold films has remained controversial. Here we report the resolution of this controversy by developing a clean CVD graphene ...
1904.08308v1
2019-05-30
A Test of Bolometric Properties of Tm-containing Crystals as a Perspective Detector for the Solar Axion Search
The $^{169}$Tm nuclide has first nuclear level at 8.41 keV with magnetic type transition to the ground state and, therefore, can be used as a target nucleus for the search of resonant absorption of solar axions. We plan to use a Tm-containing crystal of a garnet family Tm$_3$Al$_5$O$_{12}$ as a bolometric detector in o...
1905.12952v1
2019-07-13
On the generalization of the exponential basis for tensor network representations of long-range interactions in two and three dimensions
In one dimension (1D), a general decaying long-range interaction can be fit to a sum of exponential interactions $e^{-\lambda r_{ij}}$ with varying exponents $\lambda$, each of which can be represented by a simple matrix product operator (MPO) with bond dimension $D=3$. Using this technique, efficient and accurate simu...
1907.06018v1
2019-08-27
The relationship between the redox activity and electrochemical stability of solid electrolytes for solid-state batteries
All-solid-state Li-ion batteries promise safer electrochemical energy storage with larger volumetric and gravimetric energy densities. A major concern is the limited electrochemical stability of solid electrolytes and related detrimental electrochemical reactions, especially because of our restricted understanding. Her...
1908.10144v1
2019-09-30
Direct comparison of many-body methods for realistic electronic Hamiltonians
A large collaboration carefully benchmarks 20 first principles many-body electronic structure methods on a test set of 7 transition metal atoms, and their ions and monoxides. Good agreement is attained between the 3 systematically converged methods, resulting in experiment-free reference values. These reference values ...
1910.00045v2
2019-10-05
Electronic structure of bulk manganese oxide and nickel oxide from coupled cluster theory
We describe the ground- and excited-state electronic structure of bulk MnO and NiO, two prototypical correlated electron materials, using coupled cluster theory with single and double excitations (CCSD). As a corollary, this work also reports the first implementation of unrestricted periodic ab initio equation-of motio...
1910.02191v2
2019-10-18
Magnetic order and single-ion anisotropy in Tb$_3$Ga$_5$O$_{12}$
Terbium gallium garnet (TGG), Tb$_3$Ga$_5$O$_{12}$, is well known for its applications in laser optics, but also exhibits complex low-temperature magnetism that is not yet fully understood. Its low-temperature magnetic order is determined by means of time-of-flight neutron powder diffraction. It is found to be a multia...
1910.08570v1
2019-11-05
Ground-state properties of the hydrogen chain: insulator-to-metal transition, dimerization, and magnetic phases
Accurate and predictive computations of the quantum-mechanical behavior of many interacting electrons in realistic atomic environments are critical for the theoretical design of materials with desired properties, and require solving the grand-challenge problem of the many-electron Schrodinger equation. An infinite chai...
1911.01618v2