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47
2005-11-16
Spin Hamiltonian, Competing Small Energy Scales and Incommensurate Long Range Order in the Highly Frustrated Gd3Ga5O12 Garnet Antiferromagnet
Despite the availability of a spin Hamiltonian for the Gd3Ga5O12 garnet (GGG) for over twenty five years, there has so far been little theoretical insight regarding the many unusual low temperature properties of GGG. Here we investigate GGG in zero magnetic field using mean-field theory. We reproduce the spin liquid-li...
0511403v2
2006-11-20
Ill-Behaved Convergence of a Model of the Gd3Ga5O12 Garnet Antiferromagnet with Truncated Magnetic Dipole-Dipole Interactions
Previous studies have found that calculations which consider long-range magnetic dipolar interactions truncated at a finite cut-off distance Rc predict spurious (unphysical) long-range ordered phases for Ising and Heisenberg systems on the pyrochlore lattice. In this paper we show that, similar to these two cases, calc...
0611531v1
2009-06-29
A Magnetization Sensitive Potential at Garnet-Metal Interfaces
We investigate a magnetization-dependent voltage that appears at the interface between garnets and various metals. The voltage is even in the applied magnetic field and is dependent on the surface roughness and the pressure holding the surfaces together. Large variations in the size, sign and magnetic dependence are ob...
0906.5340v2
2010-06-15
Juxtaposition of Spin Freezing and Long Range Order in a Series of Geometrically Frustrated Antiferromagnetic Gadolinium Garnets
Specific heat measurements in zero magnetic field are presented on a homologous series of geometrically frustrated, antiferromagnetic, Heisenberg garnet systems. Measurements of Gd3Ga5O12, grown with isotopically pure Gd, agree well with previous results on samples with naturally abundant Gd, showing no ordering featur...
1006.2969v2
2011-01-13
Optical identification of hybrid magnetic and electric excitations in Dy3Fe5O12 garnet
Far-infrared spectra of magneto-dielectric Dy3Fe5O12 garnet were studied between 13 and 100 cm-1 and at low temperatures between 5 and 80 K. A combination of transmission, reflectivity, and rotating analyzer ellipsometry was used to unambiguously identify the type of the dipole activity of the infrared modes. In additi...
1101.2675v1
2011-09-29
Ratchet effects for paramagnetic beads above striped ferrite-garnet films
We calculate the motion of a small paramagnetic bead which is manipulated by the stripe domain pattern of a ferrite-garnet film. A model for the bead's motion in a liquid above the film is developed and used to look for ratchet solutions, where the bead acquires net coherent motion in one direction when the external fi...
1109.6491v1
2013-07-26
Synchronous versus asynchronous transport of a paramagnetic particle in a modulated ratchet potential
We present a combined experimental and theoretical study describing the dynamical regimes displayed by a paramagnetic colloidal particle externally driven above a stripe-patterned magnetic garnet film. A circularly polarized rotating magnetic field modulates the stray field of the garnet film and generates a translatin...
1307.7101v1
2013-11-01
Coherent Magnetism and Spin-Orbit Interaction in Garnet Films Probed with Femtosecond Magneto-Optical Four Wave Mixing
We report about the dephasing of the spins states in a Garnet film excited by femtosecond laser pulses. It is shown that magneto-optical four-wave-mixing signals are efficiently generated and controlled with an external static magnetic field. The self-diffraction of either two or three femtosecond pulses allows us dete...
1311.0080v1
2014-01-22
Tunable interactions between paramagnetic colloidal particles driven in a modulated ratchet potential
We study experimentally and theoretically the interactions between paramagnetic particles dispersed in water and driven above the surface of a stripe patterned magnetic garnet film. An external rotating magnetic field modulates the stray field of the garnet film and generates a translating potential landscape which ind...
1401.5754v1
2015-06-23
Effects of sublattice symmetry and frustration on ionic transport in garnet solid electrolytes
We use rigorous group-theoretic techniques and molecular dynamics to investigate the connection between structural symmetry and ionic conductivity in the garnet family of solid Li-ion electrolytes. We identify new ordered phases and order-disorder phase transitions that are relevant for conductivity optimization. Ionic...
1506.07142v1
2016-06-22
Garnet-free optical circulators monolithically integrated on spatially modified III-V quantum wells
Optical circulators are indispensable components in photonic networks that are aimed to route information in a unidirectional way among their N-ports1,2. In general, these devices rely on magneto-optical garnets3 with appreciable Verdet constants that are utilized in conjunction with other elements like permanent magne...
1606.06949v1
2016-08-07
Ultrafast photo-magnetic recording in transparent medium
Finding a conceptually new way to control the magnetic state of media with the lowest possible production of heat and simultaneously at the fastest possible time-scale is a new challenge in fundamental magnetism [1-4] as well as an increasingly important issue in modern information technology [5]. Recent results demons...
1609.05223v1
2017-02-14
Electromagnetic properties of terbium gallium garnet at millikelvin temperatures and single photon energy
Electromagnetic properties of single crystal terbium gallium garnet (TGG) are characterised from room down to millikelvin temperatures using the whispering gallery mode method. Microwave spectroscopy is performed at low powers equivalent to a few photons in energy and conducted as functions of the magnetic field and te...
1702.04081v3
2017-05-30
Enhanced magnetocaloric effect from Cr substitution in Ising lanthanide gallium garnets $Ln_3\text{CrGa}_4\text{O}_{12}$ ($Ln$ = Tb, Dy, Ho)
A detailed study on the crystal structure and bulk magnetic properties of Cr substituted Ising type lanthanide gallium garnets $Ln_3\text{CrGa}_4\text{O}_{12}$ ($Ln$ = Tb, Dy, Ho) has been carried out using room temperature powder X-Ray and neutron diffraction, magnetic susceptibility, isothermal magnetisation and heat...
1705.10547v1
2018-02-20
Comparison of the Magnetic properties of Mn3Fe2Si3O12 as a crystalline garnet and as a glass
The crystalline garnet Mn3Fe2Si3O12 and an amorphous phase of the same nominal composition are synthesized at high pressure. The magnetic properties of the two forms are reported. Both phases order antiferromagnetically. The crystalline phase exhibits a Curie-Weiss theta of -47.2 K, with a sharp ordering transition at ...
1802.07360v1
2018-08-14
Comments on "Amplifying magneto-optical photonic crystal, Appl. Phys. Lett. 97, 061116 (2010)"
This report concerns analytical solutions predicting the complex refractive indices of doped crystals, based on empirical values of the refractive indices of the dopant and the undoped crystal. An analytical approach in calculating the refractive index of Erbium doped Gadolinium Gallium Garnet was reported by another a...
1809.04413v1
2018-11-01
Magnetodielectric effects at quantum critical fields in cobalt-containing garnets
Here we present a comparative study of the magnetic and crystal chemical properties of two Co2+ containing garnets, NaCa2Co2V3O12 and CaY2Co2Ge3O12. Both phases exhibit the onset of antiferromagnetic order at 8K and 6K respectively, as well as field-induced transitions in their magnetization at 1T and around 11 T. We f...
1811.00165v1
2019-07-01
Structural phase diagram and magnetic properties of Sc-substituted rare earth ferrites R1-xScxFeO3 (R=Lu, Yb, Er, and Ho)
We have studied the structural stability of Sc-substituted rare earth (R) ferrites R1-xScxFeO3, and constructed a structural phase diagram for different R and x. While RFeO3 and ScFeO3 adopt the orthorhombic and the bixbyite structure respectively, the substituted compound R1-xScxFeO3 may be stable in a different struc...
1907.01052v1
2019-08-09
Modeling Spin Dynamics in the Singlet Ground State Garnet Ho3Ga5O12
Materials containing non-Kramers magnetic ions can show unusual quantum excitations because of the exact mapping of the two-singlet crystal-field ground state to a quantum model of Ising spins in a transverse magnetic field. Here, we model the magnetic excitation spectrum of garnet-structured Ho3Ga5O12, which has a two...
1908.03530v1
2020-08-26
Hybrid Polymer-Garnet Materials for All-Solid-State Energy Storage Devices
Hybrid electrolyte materials comprising polymer-ionic salt matrixes embedded with garnet particles constitute a promising class of materials for the realization of all-solid-state batteries. In addition to providing solutions to the safety issues inherent to current liquid electrolytes, hybrid polymer electrolytes offe...
2008.11855v2
2021-09-13
Model of the low temperature magnetic phases of gadolinium gallium garnet
The magnetic behaviour of gadolinium gallium garnet in an external magnetic field at zero temperature is considered. For high fields a classical spin model of the gadolinium ions predicts a spin configuration that is periodic at the level of the smallest repeating unit cell. The quantum version of the model is treated ...
2109.05827v1
2023-03-18
Antiferromagnetism and Ising Ground States in the Rare-earth Garnet Nd$_3$Ga$_5$O$_{12}$
In this paper, we investigate the low temperature magnetic properties of the rare-earth garnet compound Nd$_3$Ga$_5$O$_{12}$ in detail by means of magnetization, specific heat and magnetocaloric effect measurements. The magnetic thermal properties along with the crystal field calculations reveal that the Nd$^{3+}$ ions...
2303.10405v1
2023-11-11
Optimizing the tuning range of the Fermilab Recycler 53MHz RF cavities by exploiting the avoided crossing of the tuner and cavity modes
The electromagnetic eigenmodes of the Fermilab Recycler RF cavities were simulated with ACE3P running on NERSC's 'Perlmutter' supercomputer in an attempt to optimize their tuning range to comfortably support slip-stacking. A theory, based on coupled circuits and avoided crossings, was developed to explain the origins o...
2311.06571v1
2010-05-17
Vertical stratification of iron in atmospheres of blue horizontal-branch stars
The aim of this study is to search for observational evidence of vertical iron stratification in the atmosphere of fourteen blue horizontal-branch (BHB) stars. We have found from our numerical simulations that five BHB stars: B22, B186 in the globular cluster NGC 288, WF2-820, WF2-2692 in M13 and B203 in M15 show clear...
1005.2974v1
2011-01-04
The effect of varying Fe-content on transport properties of K intercalated iron selenide KxFe2-ySe2
We report the successful growth of high-quality single crystals of potassium intercalated iron selenide KxFe2-ySe2 by Bridgeman method. The effect of iron vacancies on transport properties was investigated by electrical resistivity and magnetic susceptibility measurements. With varying iron content, the system passes f...
1101.0789v1
2011-07-30
Phase Separation and Magnetic Order in K-doped Iron Selenide Superconductor
Alkali-doped iron selenide is the latest member of high Tc superconductor family, and its peculiar characters have immediately attracted extensive attention. We prepared high-quality potassium-doped iron selenide (KxFe2-ySe2) thin films by molecular beam epitaxy and unambiguously demonstrated the existence of phase sep...
1108.0069v1
2011-10-04
Transition metal impurity effect on charge and spin density in iron: Ab initio calculations and comparison with Mössbauer data
Density functional theory was applied to study influence of the isolated impurity located on the regular site of the alpha-Fe crystal on the charge and spin density (hyperfine interactions) on the iron nucleus. Calculations were performed by using both pseudopotential and the full potential methods. The scalar relativi...
1110.0717v1
2013-07-23
Exploration of iron-chalcogenide superconductors
Iron-chalcogenide compounds with FeSe(Te, S) layers did not attract much attention until the discovery of high-Tc superconductivity (SC) in the iron-pnictide compounds at the begining of 2008. Compared with FeAs-based superconductors, iron-chalcogenide superconductors have aroused enormous enthusiasm to study the relat...
1307.5991v1
2015-08-18
Elucidating the magnetic and superconducting phases in the alkali metal intercalated iron chalcogenides
The complex interdigitated phases have greatly frustrated attempts to document the basic features of the superconductivity in the alkali metal intercalated iron chalcogenides. Here, using elastic neutron scattering, energy-dispersive x-ray spectroscopy, and resistivity measurements, we elucidate the relations of these ...
1508.04482v1
2018-02-16
Manipulating surface magnetic order in iron telluride
Control of emergent magnetic orders in correlated electron materials promises new opportunities for applications in spintronics. For their technological exploitation, it is important to understand the role of surfaces and interfaces to other materials and their impact on the emergent magnetic orders. Here, we demonstra...
1802.05978v2
2022-02-17
Pressure-induced superconductivity in iron-based spin-ladder compound BaFe2+δ(S1-Sex)3
The iron-based superconductors had a significant impact on condensed matter physics. They have a common structural motif of a two-dimensional square iron lattice and exhibit fruitful physical properties as a strongly correlated electron system. During the extensive investigations, quasi-one-dimensional iron-based spin-...
2202.08525v1
2022-06-15
Anomalous Ettingshausen effect in iron-carbon alloys
We have investigated the anomalous Ettingshausen effect (AEE) in iron-carbon alloys, i.e., cast irons and steel, using the lock-in thermography. All the alloys exhibit the clear AEE-induced temperature modulation, and their anomalous Ettingshausen coefficient is an order of magnitude greater than that of the pure iron ...
2206.07322v2
2003-10-29
On the Iron content in rich nearby Clusters of Galaxies
In this paper we study the iron content of a sample of 22 nearby hot clusters observed with BeppoSAX. We find that the global iron mass of clusters is tightly related to the cluster luminosity and that the relatively loose correlation between the iron mass and the cluster temperature follows from the combination of the...
0310828v1
2005-05-26
Thermal Evolution of Supernova Iron in Elliptical Galaxies
In explaining the relative metal abundances observed in galaxy groups and clusters, it is generally assumed that all metals created by supernovae are present either in visible stars or the hot gas. We discuss here the possibility that some of the iron expelled into the hot gas by Type Ia supernovae may have radiatively...
0505527v1
2005-12-16
A Magnetic and Moessbauer Spectral Study of Core/Shell Structured Fe/Au Nanoparticles
Fe/Au nanoparticles have been chemically synthesized through a reverse micelle reaction and investigated by both conventional and synchrotron based x-ray diffraction and by magnetic and Moessbauer spectral studies. The powder x-ray diffraction patterns reveal both the presence of crystalline alpha-iron and gold and the...
0512413v1
2006-09-15
Magnetic properties of iron nanoparticles prepared by exploding wire technique
Nanoparticles of iron were prepared in distilled water using very thin iron wires and sheets, by the electro-exploding wire technique. Transmission electron microscopy reveals the size of the nanoparticles to be in the range 10 to 50 nm. However, particles of different sizes can be segregated by using ultrahigh centrif...
0609370v1
2008-12-08
The Iron abundance in Galactic Planetary Nebulae
We constrain the iron abundance in a sample of 33 low-ionization Galactic planetary nebulae (PNe) using [Fe III] lines and correcting for the contribution of higher ionization states with ionization correction factors (ICFs) that take into account uncertainties in the atomic data. We find very low iron abundances in al...
0812.1578v2
2010-06-25
Missing Iron Problem and Type Ia Supernova Enrichment of Hot Gas in Galactic Spheroids
Type Ia supernovae (Ia SNe) provide a rich source of iron for hot gas in galactic stellar spheroids. However, the expected super-solar iron abundance of the hot gas is not observed. Instead, X-ray observations often show decreasing iron abundance toward galactic central regions, where the Ia SN enrichment is expected t...
1006.4976v1
2014-05-16
A hidden reservoir of Fe/FeS in interstellar silicates?
The depletion of iron and sulphur into dust in the interstellar medium and the exact nature of interstellar amorphous silicate grains is still an open question. We study the incorporation of iron and sulphur into amorphous silicates of olivine- and pyroxene-type and their effects on the dust spectroscopy and thermal em...
1405.4208v1
2014-07-05
Fingering convection induced by atomic diffusion in stars: 3D numerical computations and applications to stellar models
Iron-rich layers are known to form in the stellar subsurface through a combination of gravitational settling and radiative levitation. Their presence, nature and detailed structure can affect the excitation process of various stellar pulsation modes, and must therefore be modeled carefully in order to better interpret ...
1407.1437v1
2021-06-27
Pulsating iron spectral features in the emission of X-ray pulsar V0332+53
We present results of phase- and time-resolved study of iron spectral features in the emission of the Be/X-ray transient pulsar V0332+53, during its type II outburst in 2004 using archival RXTE/PCA data. Coherent pulsations of both fluorescent iron line at {\approx}6.4 keV and neutral iron K-edge at {\approx}7.1 keV ha...
2106.14261v1
2021-09-21
Iron Rain: measuring the occurrence rate and origin of small iron meteoroids at Earth
We report results of a four-year survey using Electron Multiplied Charged Coupled Device (EMCCD) cameras recording 34761 two-station video meteor events complete to a limiting magnitude of +6. The survey goal was to characterize probable iron meteoroids. Using only physical properties of the meteor trajectories includi...
2109.10265v1
2010-11-21
Why the knee at 100 PeV could not be seen?
It is shown that a "second (iron) knee" in cosmic ray spectrum expected at energy about 100 PeV could not probably be found there. The reason is very simple: the position of the "iron knee" depends on an answer to the questions: "What do we see at 3-5 PeV? Is the knee seen at this energy associated with proton or iron ...
1011.4695v1
2015-04-20
Iron-Based Superconductors: current status of materials and pairing mechanism
Since the discovery of high Tc iron-based superconductors in early 2008, more than 15,000 papers have been published as a result of intensive research. This paper describes the current status of iron-based superconductors (IBSC) covering most up-to-date research progress along with the some background research, focusin...
1504.04919v1
2021-08-05
The electron-phonon coupling constant and the Debye temperature in polyhydrides of thorium, hexadeuteride of yttrium, and metallic hydrogen phase III
Milestone experimental discovery of superconductivity above 200 K in highly-compressed sulphur hydride by Drozdov (Nature 525, 73 (2015)) sparked experimental and theoretical investigations of metallic hydrides. Since then, a dozen of superconducting binary and ternary polyhydrides have been discovered. For instance, t...
2108.02610v4
2023-07-21
Ultra-fast yttrium hydride chemistry at high pressures via non-equilibrium states induced by x-ray free electron laser
Controlling the formation and stoichiometric content of desired phases of materials has become a central interest for the study of a variety of fields, notably high temperature superconductivity under extreme pressures. The further possibility of accessing metastable states by initiating reactions by x-ray triggered me...
2307.11293v1
1999-06-08
Radiative Levitation in Hot Horizontal Branch Stars
There is now considerable evidence that horizontal branch (HB) stars hotter than about 11,500 K experience an enormous enhancement of their photospheric iron abundance due to radiative levitation. In globular clusters, the photospheric iron abundance can reach values of [Fe/H] ~ +0.3, or up to two orders of magnitude h...
9906123v1
1999-06-14
Iron line afterglows: general constraints
The discovery of a powerful and transient iron line feature in the X-ray afterglow spectra of gamma-ray bursts would be a major breakthrough for understanding the nature of their progenitors, strongly suggesting the presence of a large, iron rich, mass in the vicinity of the burst event. Model-independent limits to the...
9906234v1
1999-06-14
Iron line afterglows: how to produce them
We discuss how a powerful iron line emission can be produced if ~1-5 iron rich solar masses are concentrated in the close vicinity of the burst. Recombination, thermal and fluorescent reflection are discussed. We find that recombination suffers the high Compton temperature of the plasma while the other two scenarios ar...
9906235v1
2003-01-31
Non-collinear magnetism in iron at high pressures
Using a first principles based, magnetic tight-binding total energy model, the magnetization energy and moments are computed for various ordered spin configurations in the high pressure polymorphs of iron (fcc, or $\gamma$-Fe, and hcp, or $\epsilon$-Fe), as well ferromagnetic bcc iron ($\alpha$-Fe). For hcp, a non-coll...
0301615v1
2004-01-16
Ferromagnetism in Fe-doped SnO2 thin films
Thin films grown by pulsed-laser deposition from targets of Sn0.95Fe0.05O2 are transparent ferromagnets with Curie temperature and spontaneous magnetization of 610 K and 2.2 Am2kg-1, respectively. The 57Fe Mossbauer spectra show the iron is all high-spin Fe3+ but the films are magnetically inhomogeneous on an atomic sc...
0401293v1
2008-07-29
The effect of pressure and spin on the isotopic composition of ferrous iron dissolved in periclase and silicate perovskite
We perform density functional calculations of the equilibrium 57Fe/54Fe ratios for ferrous iron dissolved in periclase and MgSiO3 perovskite at the pressures and temperatures of the Earth's mantle. Pressure increases the partitioning of 57Fe into both phases by a factor of three from the Earth's surface to the core-man...
0807.4742v1
2008-08-13
Coreless Terrestrial Exoplanets
Differentiation in terrestrial planets is expected to include the formation of a metallic iron core. We predict the existence of terrestrial planets that have differentiated but have no metallic core--planets that are effectively a giant silicate mantle. We discuss two paths to forming a coreless terrestrial planet, wh...
0808.1908v1
2009-07-01
Role of soft-iron impellers on the mode selection in the VKS dynamo experiment
A crucial point for the understanding of the von-K\'arm\'an-Sodium (VKS) dynamo experiment is the influence of soft-iron impellers. We present numerical simulations of a VKS-like dynamo with a localized permeability distribution that resembles the shape of the flow driving impellers. It is shown that the presence of so...
0907.0123v2
2009-08-08
A Unified Description of Cuprate and Iron Arsenide Superconductors
We propose a unified description of cuprate and iron-based superconductivity. Consistency with magnetic structure inferred from neutron scattering implies significant constraints on the symmetry of the pairing gap for the iron-based superconductors. We find that this unification requires the orbital pairing formfactors...
0908.1147v1
2009-08-27
A new 111 type iron pnictide superconductor LiFeP
A new iron pnictide LiFeP superconductor was found. The compound crystallizes into a Cu2Sb structure containing an FeP layer showing superconductivity with maximum Tc of 6K. This is the first 111 type iron pnictide superconductor containing no arsenic. The new superconductor is featured with itinerant behavior at norma...
0908.4043v1
2009-08-29
Spin-Phonon Coupling in Iron Pnictide Superconductors
The magnetic moment in the parent phase of the iron-pnictide superconductors varies with composition even when the nominal charge of iron is unchanged. We propose the spin-lattice coupling due to the magneto-volume effect as the primary origin of this effect, and formulate a Landau theory to describe the dependence of ...
0908.4361v1
2011-10-03
Calculated phonon spectra of paramagnetic iron at the alpha-gamma phase transition
We compute lattice dynamical properties of iron at the bcc-fcc phase transition using dynamical mean-field theory implemented with the frozen-phonon method. Electronic correlations are found to have a strong effect on the lattice stability of paramagnetic iron in the bcc phase. Our results for the structural phase stab...
1110.0439v1
2013-07-22
Angle-resolved photoemission spectroscopy study on iron-based superconductors
Angle-resolved photoemission spectroscopy (ARPES) has played an important role in determining the band structure and the superconducting gap structure of iron-based superconductors. Here from the ARPES perspective, we briefly review the main results from our group in the recent years on the iron-based superconductors a...
1307.5754v3
2014-07-01
Explaining Mercury's Density through Magnetic Erosion
In protoplanetary disks, dust grains rich in metallic iron can attract each other magnetically. If they are magnetized to values near saturation, the magnetically induced collision speeds are high enough to knock off the non-magnetized, loosely bound silicates. This process enriches the surviving portions of the dust g...
1407.0274v1
2015-05-22
Oxygen-annealing effects on superconductivity in polycrystalline Fe1-xTe1-ySey
Superconductivity in anti-PbO-type iron chalcogenides Fe1-xTe1-ySey (x = 0, 0.1, y = 0.1 0.4) depends on the amount (x) of interstitial iron atoms located between the FeTe1-ySey layers. Non-superconducting samples of nominal Fe1.1Te1-ySey convert to superconductors with critical temperatures up to 14 K after annealing ...
1505.06066v1
2015-10-06
Iron emission line from the spiral galaxy M101
Archival Suzaku data of the face-on spiral galaxy M101 were analyzed. An intense emission line at 6.72^{+0.10}_{-0.12} keV was detected in the central region. This line is identified with a K-line from He-like iron, which indicates the existence of a thin thermal plasma with a temperature of several keV. The iron line ...
1510.01483v1
2015-10-29
Effect of antimony substitution in iron pnictide compounds
In the present study we have examined the effect of negative chemical pressure in iron pnictides. We have synthesized substitution series replacing arsenic by antimony in a number of 1111- and 122-iron arsenides and present their crystallographic and physical properties. The SDW transition temperature in LaFeAs$_{\math...
1510.08665v1
2015-12-03
Non-LTE iron abundances in cool stars: The role of hydrogen collisions
In the aim of determining accurate iron abundances in stars, this work is meant to empirically calibrate H-collision cross-sections with iron, where no quantum mechanical calculations have been published yet. Thus, a new iron model atom has been developed, which includes hydrogen collisions for excitation, ionization a...
1512.01118v1
2016-09-14
Iron Isotope Effect in SmFeAsO0.65 and SmFeAsO0.77H0.12 Superconductors: A Raman Study
We report the inelastic light scattering studies on SmFeAsO0.65 and SmFeAsO0.77H0.12 with iron isotopes namely 54Fe and 57Fe. In both of these systems under investigation we observed a significant shift in the frequency of the phonon modes associated with the displacement of Fe atoms around ~ 200 cm-1. The observed shi...
1609.04183v1
2017-03-31
Longitudinal modes of spin fluctuations in iron-based superconductors
Iron-based superconductors can exhibit different magnetic ground states and are in a critical magnetic region where frustrated magnetic interactions strongly compete with each other. Here we investigate the longitudinal modes of spin fluctuations in an unified effective magnetic model for iron-based superconductors. We...
1703.10721v2
2018-01-10
The IRON Project: Photoionization of Fe ions
The IRON Project, initiated in 1991, aims at two main objectives, i) study the characteristics of and calculate large-scale high accuracy data for atomic radiative and collisional processes, and ii) application in solving astrophysical problems. It focuses on the complex iron and iron-peak elements commonly observed in...
1801.05410v1
2018-06-08
Helium-iron compounds at terapascal pressures
We investigate the binary phase diagram of helium and iron using first-principles calculations. We find that helium, which is a noble gas and inert at ambient conditions, forms stable crystalline compounds with iron at terapascal pressures. A FeHe compound becomes stable above 4 TPa, and a FeHe$_2$ compound above 12 TP...
1806.03017v1
2018-11-09
Topological quantum states of matter in iron-based superconductors: From concepts to material realization
We review recent progress in the explorations of topological quantum states of matter in iron-based superconductors. In particular, we focus on the nontrivial topology existing in the band structures and superconducting states of iron's 3d orbitals. The basic concepts, models, materials and experimental results are rev...
1811.03802v1
2019-02-24
Spin interactions and magnetic order in the iron oxychalcogenides BaFe2Q2O
The ability to tune the iron chalcogenides BaFe2Q3 from Mott insulators, to metals and then superconductors with applied pressure has renewed interest in low-dimensional iron chalcogenides and oxychalcogenides. We report here a combined experimental and theoretical study on the iron oxychalcogenides BaFe2Q2O (Q=S, Se) ...
1902.09035v2
2021-11-04
Sequence of superconducting states in field cooled $FeCr_2S_4$
In the present article we discuss theoretically the emergence of superconductivity in field cooled $FeCr_2S_4$. The chromium electrons form a triplet $t_{2g}$ states and due to antiferromagnetic exchange with the iron spins have Zeeman splitting. Applied, during preparation, magnetic field along the moment of iron ions...
2111.02765v1
2023-07-03
Cosmic abundance of iron
I explore a possibility to estimate an upper limit of the current iron abundance of the barion matter. The upper limit is determined by the minimal iron abundance, at which the gamma-ray background, produced by the decay of $^{56}$Ni synthesised in the Universe to date, contradicts the observational MeV gamma-ray backg...
2307.00944v1
2014-08-19
Soft chemical control of superconductivity in lithium iron selenide hydroxides Li1-xFex(OH)Fe1-ySe
Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1-xFex(OH)Fe1-ySe (x ~ 0.2; 0.02 < y < 0.15) with a wide range of iron site vacancy concentrations in the iron selenide layers. This iron vacancy concentration is revealed as the only significant compositional variable and as the key para...
1408.4350v2
1997-02-04
Roles of SNIa and SNII in ICM Enrichment
Based on ASCA observations Mushotzky et al. (1996, ApJ 466, 686) have recently derived the relative-abundance ratios of $\alpha$-elements to iron, [\alpha/Fe] \simeq 0.2-0.3$, for four rich clusters, and have suggested that the origin of metals in an intra-cluster medium (ICM) is not a type-Ia supernovae (SNIa), but a ...
9702036v1
2008-08-09
Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases
The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular "reactive oxygen species" (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations....
0808.1371v1
2008-11-24
The optical/X-ray connection: ICM iron content and galaxy optical luminosity in 20 galaxy clusters
X-ray observations of galaxy clusters have shown that the intra-cluster gas has iron abundances of about one third of the solar value. These observations also show that part (if not all) of the intra-cluster gas metals were produced within the member galaxies. We present a systematic analysis of 20 galaxy clusters to e...
0811.3936v1
2009-10-25
Pair-breaking in iron-pnictides
The puzzling features of the slopes of the upper critical field at the critical temperature $T_c$, $H^\prime_{c2}(T_c)\propto T_c$, and of the specific heat jump $\Delta C\propto T_c^3$ of iron-pnictides are interpreted as caused by a strong pair-breaking.
0910.4728v1
2009-12-28
Iron pnictide superconductors: Electrons on the verge
An optical analysis reveals that the electronic correlations in the `parent' compounds of the iron pnictide superconductors are sufficiently strong to significantly impede the mobility of the electrons.
0912.4989v1
2010-05-19
Rusty old stars: a source of the missing interstellar iron?
Iron, the Universe's most abundant refractory element, is highly depleted in both circumstellar and interstellar environments, meaning it exists in solid form. The nature of this solid is unknown. In this Letter, we provide evidence that metallic iron grains are present around oxygen-rich AGB stars, where it is observa...
1005.3489v1
2010-10-14
Bipolaron Model of the Superconductivity of an Iron-Based Layered Compound LnO_{1-x}F_xFePn (Ln =La, Sm, Nd, Pr, Ce, Pn=P, As)
A bipolaron model is proposed as a superconductivity mechanism for iron-based superconductivity. The results are consistent with the experiments.
1010.3026v1
2012-02-19
Spin fluctuations and superconductivity in powders of Fe_1+xTe_0.7Se_0.3 as a function of interstitial iron concentration
Using neutron inelastic scattering, we investigate the role of interstitial iron on the low-energy spin fluctuations in powder samples of Fe_{1+x}Te_{0.7}Se_{0.3}. We demonstrate how combining the principle of detailed balance along with measurements at several temperatures allows us to subtract both temperature-indepe...
1202.4152v1
2016-05-06
Iron: A Key Element for Understanding the Origin and Evolution of Interstellar Dust
The origin and depletion of iron differ from all other abundant refractory elements that make up the composition of the interstellar dust. Iron is primarily synthesized in Type Ia supernovae (SNe Ia) and in core collapse supernovae (CCSN), and is present in the outflows from AGB stars. Only the latter two are observed ...
1605.01957v1
2018-06-25
Fermi surface pockets in electron-doped iron superconductor by Lifshitz transition
The Fermi surface pockets that lie at the corner of the two-iron Brillouin zone in heavily electron-doped iron selenide superconductors are accounted for by an extended Hubbard model over the square lattice of iron atoms that includes the principal 3d xz and 3d yz orbitals. At half filling, and in the absence of intra-...
1806.09322v2
2021-10-22
Thermal conductivity of oxide scale and its components in the range from 0 C to 1300 C: Generalized estimates with account for movability of phase transitions
The data of different authors on the thermal conductivity of wustite Fe1-xO, magnetite F3O4, hematite Fe2O3 and pure iron are systematized. The generalized values are described by piecewise smooth functions containing as varying parameters the temperatures of magnetiv and polymorphic (for iron) transformations as well ...
2110.11632v1
2021-10-28
A Quantitative Analysis of the Ignition Characteristics of Fine Iron Particles
Ignition of iron particles in an oxidizing environment marks the onset of a self-sustained combustion. The objective of the current study is to quantitatively examine the ignition characteristics of fine iron particles governed by the kinetics of solid-phase iron oxidation. The oxidation rates are inversely proportiona...
2110.15461v2
1996-08-23
NMR in copper-Oxide Metals
The anomalous part of the NMR relaxation rate of coppernuclei in the normal state of copper-oxide metals is calculated using the orbital magnetic parts of the fluctuations derived in a recent theory to explain the long wavelength transport anomalies. Oxygen and Yttrium reside on lattice sites at which the anomalous con...
9608109v1
1996-12-09
From microscopic description to statistical mechanics of Cu-O chain fragments in the high-Tc superconductors REBa_2Cu_3O_{6+x}
The oxygen deficient CuO_x planes of the high-Tc superconductors REBa_2Cu_3O_{6+x} (RE denotes a rare-earth atom or yttrium) are studied. Starting from the Emery model for the Cu-O chain fragments, an extended ASYNNNI model is proposed to describe the statistical mechanics of the CuO_x planes. The model is analysed by ...
9612072v1
1998-09-03
Fermi Surface as the Driving Mechanism for Helical Antiferromagnetic Ordering in Gd-Y Alloys
The first direct experimental evidence for the Fermi surface (FS) driving the helical antiferromagnetic ordering in a gadolinium-yttrium alloy is reported. The presence of a FS sheet capable of nesting is revealed, and the nesting vector associated with the sheet is found to be in excellent agreement with the periodici...
9809063v1
1999-03-04
Parameter-free expression for superconducting Tc in cuprates
A parameter-free expression for the superconducting critical temperature of layered cuprates is derived which allows us to express Tc in terms of experimentally measured parameters. It yields Tc values observed in about 30 lanthanum, yttrium and mercury-based samples for different levels of doping. This remarkable agre...
9903071v1
1999-06-11
Induced spin polarisation in a ferromagnetic gadolinium-yttrium alloy
The first direct evidence of an induced spin moment in Gd(62.4)Y(37.6) is presented. This additional moment, of 0.16 +/- 0.03 Bohr magnetons, arises from polarisation of Y electrons in the alloy. The moment was detected in a Compton scattering experiment via the measurement of the one dimensional projection of the mome...
9906171v1
2001-06-18
Disorder induced hexagonal-orthorhombic transition in (Y,Gd)MnO3
We show that the transition in AMnO3 from the orthorhombic perovskite phase to the hexagonal phase is promoted by inducing disorder on the A-site. The gap between the orthorhombic and the hexagonal phase is widened for disordered, mixed yttrium-gadolinium manganite samples. At the cost of the orthorhombic phase a two p...
0106335v1
2002-02-09
Fermi surface of yttrium
Electron-positron momentum densities in Y, reconstructed from two-dimensional angular correlation of annihilation radiation spectra, are compared with the theoretical predictions of fully-relativistic augmented plane-wave calculations. Knowledge of the theoretical densities and of the effects on them of certain symmetr...
0202157v2
2002-07-29
Electronic Structure of the YH3 Phase from Angle-Resolved Photoemission Spectroscopy
Yttrium can be loaded with hydrogen up to high concentrations causing dramatic structural and electronic changes of the host lattice. We report on angle-resolved photoemission experiments of the Y trihydride phase. Most importantly, we find the absence of metal d-bands at the Fermi level and a set of flat, H-induced ba...
0207680v1
2002-09-10
On the reliability of various enhancement theories for a description of electron-positron densities in metals
Four theoretical approaches to calculate momentum densities of electron-positron annihilation pairs (MDAP) in crystalline solids are confronted with 3D densities reconstructed from two-dimensional angular correlation (2D-ACAR) data for copper, chromium, and yttrium. It is shown that the Bloch-modified ladder theory, in...
0209235v1
2004-01-28
Effects of Substituting Calcium for Yttrium on the Superconducting Properties of YBa2Cu3Oz Bulk Samples
We report systematic studies of AC magnetic susceptibility and transport properties of Y(1-x)Ca(x)Ba2Cu3Oz bulk samples with 0\leq x\leq 0.4. Single phase materials, reduction of carrier concentration and decrease of Tc to 85 K were obtained at doping levels up to 20%. For Y0.7Ca0.3Ba2Cu3Oz sample the improvement of gr...
0401584v1
2011-11-10
High-Temperature Superconductivity Mechanism for Cuprates
Egorov and March plotted the product of resistivity and the copper spin-lattice relaxation time vs. temperature for yttrium barium copper oxide finding a minimum at temperature T greater than the superconducting temperature, heralding an electronic phase change which can be interpreted as the formation of a "preformed"...
1111.2560v1
2013-09-04
Unexpected colloid-like supernatant from liquid-phase ball-milling graphite using miscible solutions as solvents: a failure analysis
Ball-milling graphite was conducted in miscible solutions with the purpose to exfoliate graphene. Colloid-like stable supernatants were unexpectedly obtained. Followed were the characterizations with Scanning electronic microscopy, Thermogravimetric analysis, X-ray diffraction and Elemental dispersive X-ray mapping to ...
1309.1056v2
2014-11-25
Simulation study of negative thermal expansion in yttrium tungstate Y2W3O12
A simulation study of negative thermal expansion in Y2W3O12 was carried out using calculations of phonon dispersion curves through the application of density functional perturbation theory. The mode eigenvectors were mapped onto flexibility models and results compared with calculations of the mode Gruneisen parameters....
1411.7071v1
2015-11-21
Theoretical description of slow non-monotonic relaxation processes in Al-Y melts
The slow non-monotonic relaxation processes, which have been recently fixed in Al-Y melts, are described theoretically. The theoretical description is based on the Cahn-Hilliard theory and functional methods of non-equilibrium dynamics. In terms of the suggested approach the reasons of this relaxation kinetics are non-...
1511.06908v1
2016-11-17
Thin Film growth of Solid State materials
Magnetron sputtering has also been used to deposit thin films of some materials and it has significant technological importance. A modeling on deposition of epitaxial thin films of Yttrium Stabilized Zirconia (YSZ) was done the diffusion of adatom on the surface were studies. There exists a strong interaction of ions f...
1611.07926v1