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2014-12-23
Pressure effects on the superconductivity of HfPd2Al Heusler compound: Experimental and theoretical study
Polycrystalline HfPd2Al has been synthesized using the arc-melting method and studied under ambient pressure conditions by x-ray diffraction from room temperature up to 450^oC. High pressure x-ray diffraction up to 23 GPa was also performed using Diacell-type membrane diamond anvil cells. The estimated linear thermal e...
1412.7362v2
2015-01-27
Transition from semiconducting to metallic-like conducting and weak antilocalization effect in single crystals of LuPtSb
High quality half-Heusler single crystals of LuPtSb have been synthesized by a Pb flux method. The temperature dependent resistivity and Hall effects indicate that the LuPtSb crystal is a p-type gapless semiconductor showing a transition from semiconducting to metallic conducting at 150 K. Moreover, a weakly temperatur...
1501.06714v1
2015-02-02
Large linear magnetoresistance and weak anti-localization in Y(Lu)PtBi topological insulators
Topological insulators are new kind of Dirac materials that possess bulk insulating and surface conducting behavior. They are basically known for their unique electronic properties at the surface. Here we present the magneto-transport properties of our high quality single crystalline Y(Lu)PtBi Heusler topological insul...
1502.00604v2
2015-03-12
Shubnikov-de Haas oscillations, weak antilocalization effect and large linear magnetoresistance in the putative topological superconductor LuPdBi
We present electronic transport and magnetic properties of single crystals of semimetallic half-Heusler phase LuPdBi, having theoretically predicted band inversion requisite for nontrivial topological properties. The compound exhibits superconductivity below a critical temperature $T_{\rm c}=1.8\,$K, with a zero-temper...
1503.03697v1
2015-04-14
Reduced thermal conductivity of TiNiSn/HfNiSn superlattices
Diminution of the thermal conductivity is a crucial aspect in thermoelectric research. We report a systematic and significant reduction of the cross-plane thermal conductivity in a model system consisting of DC sputtered TiNiSn and HfNiSn half-Heusler superlattices. The reduction of $\kappa$ is measured by the 3$\omega...
1504.03468v2
2015-06-07
Experimental observation of the interaction of propagating spin waves with Néel domain walls in a Landau domain structure
The interaction of propagating dipolar spin waves with magnetic domain walls is investigated in square-shaped microstructures patterned from the Heusler compound Co$_2$Mn$_{0.6}$Fe$_{0.4}$Si. Using magnetic force microscopy, the reversible preparation of a Landau state with four magnetic domains separated by N\'eel dom...
1506.02303v1
2015-10-21
Unconventional superconductivity in YPtBi and related topological semimetals
YPtBi, a topological semimetal with very low carrier density, was recently found to be superconducting below $T_\mathrm{c} = 0.77$\,K. In the conventional theory, the nearly vanishing density of states around the Fermi level would imply a vanishing electron-phonon coupling and would therefore not allow for superconduct...
1510.06209v2
2015-12-18
Antiferromagnetism and superconductivity in the half-Heusler semimetal HoPdBi
We observed the coexistence of superconductivity and antiferromagnetic order in the single-crystalline ternary pnictide HoPdBi, a plausible topological semimetal. The compound orders antiferromagnetically at $T_N =$1.9 K and exhibits superconductivity below $T_c =$0.7 K, which was confirmed by magnetic, electrical tran...
1512.05972v1
2016-04-25
Room temperature tetragonal noncollinear antiferromagnet Pt$_2$MnGa
Here we present the tetragonal stoichiometric Heusler compound Pt$_2$MnGa with the noncollinear AFM order stable up to 350 K. It is resolved by the neutron diffraction as a helical spiral propagating along the tetragonal axis. Ab-initio calculations suggest a pure exchange origin of the spiral and explain its helical c...
1604.07137v1
2016-05-01
First clear evidence of quantum chaos in the bound states of an atomic nucleus
We study the spectral fluctuations of the $^{208}$Pb nucleus using the complete experimental spectrum of 151 states up to excitation energies of $6.20$ MeV recently identified at the Maier-Leibnitz-Laboratorium at Garching, Germany. For natural parity states the results are very close to the predictions of Random Matri...
1605.00210v1
2016-07-01
Generation of Spin Currents by Magnetic Field in $\mathcal{T}$- and $\mathcal{P}$-Broken Materials
Pure spin currents carry information in quantum spintronics and could play an essential role in the next generation low-energy-consumption electronics. Here we theoretically predict that the magnetic field can induce a quantum spin current without a concomitant charge current in metals without time reversal symmetry $\...
1607.00116v1
2016-07-01
Ultra-high vacuum compatible induction-heated rod casting furnace
We report the design of a radio-frequency induction-heated rod casting furnace that permits the preparation of polycrystalline ingots of intermetallic compounds under ultra-high vacuum compatible conditions. The central part of the system is a bespoke water-cooled Hukin crucible supporting a casting mold. Depending on ...
1607.00821v1
2016-09-22
Quantum-Many-Body Intermetallics: Phase Stability of Fe$_3$Al and Small-Gap Formation in Fe$_2$VAl
Various intermetallic compounds harbor subtle electronic correlation effects. To elucidate this fact for the Fe-Al system, we perform a realistic many-body investigation based on the combination of density functional theory with dynamical mean-field theory in a charge self-consistent manner. A better characterization a...
1609.06928v2
2016-10-21
Giant Positive Magnetoresistance and field-induced metal insulator transition in Cr2NiGa
We report here the magneto-transport properties of the newly synthesized Heusler compound Cr2NiGa which crystallizes in a disordered cubic B2 structure belonging to Pm-3m space group. The sample is found to be paramagnetic down to 2 K with metallic character. On application of magnetic field, a significantly large incr...
1610.06771v1
2016-11-13
Topological Materials: Weyl Semimetals
Topological insulators and topological semimetals are both new classes of quantum materials, which are characterized by surface states induced by the topology of the bulk band structure. Topological Dirac or Weyl semimetals show linear dispersion round nodes, termed the Dirac or Weyl points, as the three-dimensional an...
1611.04182v2
2017-01-06
Generic coexistence of Fermi arcs and Dirac cones on the surface of time-reversal invariant Weyl semimetals
The hallmark of Weyl semimetals is the existence of open constant-energy contours on their surface -- the so-called Fermi arcs -- connecting Weyl points. Here, we show that for time-reversal symmetric realizations of Weyl semimetals these Fermi arcs in many cases coexist with closed Fermi pockets originating from surfa...
1701.01660v3
2017-03-04
Impact of Anisotropy on Antiferromagnet Rotation in Heusler-type Ferromagnet/Antiferromagnet Epitaxial Bilayers
We report the magnetotransport properties of ferromagnet (FM)/antiferromagnet (AFM) Fe$_2$CrSi/Ru$_2$MnGe epitaxial bilayers using current-in-plane configurations. Above the critical thickness of the Ru$_2$MnGe layer to induce exchange bias, symmetric and asymmetric curves were observed in response to the direction of ...
1703.01406v2
2017-03-15
Two-channel conduction in YbPtBi
We investigated transport, magnetotransport, and broadband optical properties of the half-Heusler compound YbPtBi. Hall measurements evidence two types of charge carriers: highly mobile electrons with a temperature-dependent concentration and low-mobile holes; their concentration stays almost constant within the invest...
1703.05202v1
2017-03-20
Topological phase transitions in multi-component superconductors
We study the phase transition between a trivial and a time-reversal-invariant topological superconductor in a single-band system. By analyzing the interplay of symmetry, topology and energetics, we show that for a generic normal state band structure, the phase transition occurs via extended intermediate phases in which...
1703.06880v2
2017-07-23
Majorana surface modes of nodal topological pairings in spin-$\frac{3}{2}$ semi-metals
Multi-component electronic systems can appear in solid state systems with active orbital band structures. They exhibit richer structures of topological superconductivity beyond the conventional scenarios of spin singlet and triplet pairings in spin-$\frac{1}{2}$ systems. Examples include the half-Heusler compounds RPtB...
1707.07261v3
2017-11-07
YbPd$_2$In: a promising candidate to strong entropy accumulation at very low temperature
We report on synthesis, crystal structure, magnetic, thermodynamic and transport properties of the new compound YbPd$_2$In, crystallizing as a Heusler structure type. A trivalent state of the rare earth was determined by fitting the magnetic susceptibility with a Curie-Weiss law. This compound is characterized by showi...
1711.02335v3
2017-11-11
Planar Hall effect in the Weyl semimetal GdPtBi
Observation of Weyl and Dirac Fermions in condensed matter systems is one of the most important discoveries. Among the very few available tools to characterize Weyl semimetals through electrical transport, negative magnetoresistance is most commonly used. Considering shortcomings of this method, new tools to characteri...
1711.04133v2
2017-11-16
Using the Callaway model to deduce relevant phonon scattering processes: The importance of phonon dispersion
The thermal conductivity $\kappa$ of a material is an important parameter in many different applications. Optimization strategies of $\kappa$ often require insight into the dominant phonon scattering processes of the material under study. The Callaway model is widely used as an experimentalist's tool to analyze the lat...
1711.06153v3
2017-11-27
Characterization of Spin-Transfer-Torque effect induced magnetization dynamics driven by short current pulses
We present a time-resolved study of the magnetization dynamics in a microstructured Cr$|$Heusler$|$Pt waveguide driven by the Spin-Hall-Effect and the Spin-Transfer-Torque effect via short current pulses. In particular, we focus on the determination of the threshold current at which the spin-wave damping is compensated...
1711.09647v1
2017-12-30
Singlet-Quintet Mixing in Spin-Orbit Coupled Superconductors with j=3/2 Fermions
In non-centrosymmetric superconductors, spin-orbit coupling can induce an unconventional superconducting state with a mixture of s-wave spin-singlet and p-wave spin-triplet channels, which leads to a variety of exotic phenomena, including anisotropic upper critical field, magnetoelectric effect, topological superconduc...
1801.00083v2
2018-01-12
Irradiated three-dimensional Luttinger semimetal: A factory for engineering Weyl semimetals
We study the interaction between elliptically polarized light and a three-dimensional Luttinger semimetal with quadratic band touching using Floquet theory. In the absence of light, the touching bands can have the same or the opposite signs of the curvature; in each case, we show that simply tuning the light parameters...
1801.04287v1
2018-01-17
Multiple Triple-Point Fermions in Heusler Compounds
Using the density functional theoretical calculations, we report a new set of topological semimetals X$_{2}$YZ (X = \{Cu, Rh, Pd, Ag, Au, Hg\}, Y = \{Li, Na, Sc, Zn, Y, Zr, Hf, La, Pr, Pm, Sm, Tb, Dy, Ho, Tm\} and Z =\{Mg, Al, Zn, Ga, Y, Ag, Cd, In, Sn, Ta, Sm\}), which show the existence of multiple topological triple...
1801.05699v1
2018-03-02
Linear-in-frequency optical conductivity in GdPtBi due to transitions near the triple points
The complex optical conductivity of the half-Heusler compound GdPtBi is measured in a frequency range from 20 to 22 000 cm$^{-1}$ (2.5 meV - 2.73 eV) at temperatures down to 10 K in zero magnetic field. We find the real part of the conductivity, $\sigma_{1}(\omega)$, to be almost perfectly linear in frequency over a br...
1803.00840v2
2018-03-07
Edge currents as a probe of the strongly spin-polarized topological noncentrosymmetric superconductors
Recently the influence of antisymmetric spin-orbit coupling has been studied in novel topological superconductors such as half-Heuslers and artificial hetero-structures. We investigate the effect of Rashba and/or Dresselhaus spin-orbit couplings on the band structure and topological properties of a two-dimensional nonc...
1803.02591v1
2018-03-09
Strong anomalous Nernst effect in collinear magnetic Weyl semimetals without net magnetic moments
We predict a large anomalous Nernst effect in the inverse Heusler compensated ferrimagnets Ti$_2$Mn$X$ ($X$=Al,Ga,In) with vanishing net magnetic moments. Though the net magnetic moment is zero, the Weyl points in these systems lead to a large anomalous Nernst conductivity (ANC) due to the lack of a magnetic sublattice...
1803.03439v3
2018-05-15
Spincaloric properties of epitaxial Co$_2$MnSi/MgO/Co$_2$MnSi magnetic tunnel junctions
The electronic transport and spincaloric properties of epitaxial magnetic tunnel junctions with half-metallic Co$_2$MnSi Heusler electrodes, MgO tunneling barriers, and different interface terminations are investigated by using first-principles calculations. A new approach to spincaloric properties is presented that ci...
1805.05805v1
2018-05-18
Search for alternative magnetic tunnel junctions based on all-Heusler stacks
By imposing the constraints of structural compatibility, stability and a large tunneling magneto-resistance, we have identified the Fe$_3$Al/BiF$_3$/Fe$_3$Al stack as a possible alternative to the well-established FeCoB/MgO/FeCoB in the search for a novel materials platform for high-performance magnetic tunnel junction...
1805.08603v1
2018-09-19
Structure-property relationship of Co$_2$MnSi thin films in response to He$^+$ -irradiation
We investigated the structure-property relationship of Co$_2$MnSi Heusler thin films upon the irradiation with He$^+$ ions. The variation of the crystal structure with increasing ion fluence has been probed using nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM), and associated with the corres...
1809.07097v1
2021-07-02
Investigating 3D printed Cartesian Divers
Despite the difficult circumstances due to the COVID-19 pandemics, physics students can tackle interesting questions that are part of physics competitions as the German Physicists' Tournament (GPT) 2020. Due to the COVID-19 pandemics in 2020, many competitions such as the GPT are held online. Furthermore, the usual opt...
2107.00950v1
2018-10-08
Porosity-mediated High-performance Thermoelectric Materials
Whether porosity can effectively improve thermoelectric performance is still an open question. Herein we report that thermoelectric performance can be significantly enhanced by creating porosity in n-type Mg3.225Mn0.025Sb1.5Bi0.49Te0.01, with a ZT of ~0.9 at 323 K and ~1.6 at 723 K, making the average ZT much higher fo...
1810.03356v2
2019-07-29
Strain engineered higher order topological phases for spin-3/2 Luttinger fermions
Recently, the notion of topological phases of matter has been extended to higher-order incarnations, supporting gapless modes on even lower dimensional boundaries, such as corners and hinges. We here identify a collection of cubic spin-3/2 fermions with biquadratic touching of Kramers degenerate valence and conduction ...
1907.12568v2
2019-10-09
Superconductivity from Coulomb repulsion in three-dimensional quadratic band touching Luttinger semimetals
We study superconductivity driven by screened Coulomb repulsion in three-dimensional Luttinger semimetals with a quadratic band touching and strong spin-orbit coupling. In these semimetals, the Cooper pairs are formed by spin-3/2 fermions with non-trivial wavefunctions. We numerically solve the linear Eliashberg equati...
1910.04189v2
2012-09-19
Revealing the spin and symmetry properties of the buried Co2MnSi/MgO interface by low energy spin-resolved photoemission
We present a novel approach to study the spin and symmetry electronic properties of buried interfaces using low-energy spin-resolved photoemission spectroscopy. We show that this method is sensitive to interfaces buried below more than 20ML (~4nm) MgO, providing a powerful tool for the non-destructive characterization ...
1209.4368v1
2012-09-25
A p-type Heusler compound: Growth, structure, and properties of epitaxial thin NiYBi films on MgO(100)
Epitaxial semiconducting NiYBi thin films were directly prepared on MgO(100) substrates by magnetron sputtering. The intensity ratio of the (200) and (400) diffraction peaks, I(200)/I(400) = 2.93, was close to the theoretical value (3.03). The electronic structure of NiYBi was calculated using WIEN2k and a narrow indir...
1209.5707v1
2012-09-25
Electronic and crystalline structures of zero band-gap PdLuBi thin films grown epitaxially on MgO(100)
Thin films of the proposed topological insulator PdLuBi - a Heusler compound with the C1b structure - were prepared on Ta-Mo-buffered MgO(100) substrates by co-sputtering from PdBi2 and Lu targets. Epitaxial growth of high-quality PdLuBi films was confirmed by X-ray spectrometry and reflection high-energy electron diff...
1209.5710v1
2014-06-25
Magnetic structure of GdBiPt: A candidate antiferromagnetic topological insulator
A topological insulator is a state of matter which does not break any symmetry and is characterized by topological invariants, the integer expectation values of non-local operators. Antiferromagnetism on the other hand is a broken symmetry state in which the translation symmetry is reduced and time reversal symmetry is...
1406.6663v1
2018-02-20
Thermoelectricity in correlated narrow-gap semiconductors
We review many-body effects, their microscopic origin, as well as their impact onto thermoelectricity in correlated narrow-gap semiconductors. Members of this class---such as FeSi and FeSb$_2$---display an unusual temperature dependence in various observables: insulating with large thermopowers at low temperatures, the...
1802.07220v1
2018-08-17
Magnetic and structural properties of Co$_2$MnSi based Heusler compound
The influence of antisite disorder occupancies on the magnetic properties of the half-metallic Co$_2$MnSi compound was studied by experimental techniques and first-principles calculations. The neutron diffraction studies show almost identical amount of Mn and Co disorders of 6.5\% and 7.6\%, which was found to be in go...
1808.05743v3
2018-12-05
Majorana multipole response of topological superconductors
In contrast to elementary Majorana particles, emergent Majorana fermions (MFs) in condensed-matter systems may have electromagnetic multipoles. We developed a general theory of magnetic multipoles for surface helical MFs on time-reversal-invariant superconductors. The results show that the multipole response is governe...
1812.01857v1
2018-12-18
Optical response of Luttinger semimetals in the normal and superconducting states
We investigate the optical response properties of three-dimensional Luttinger semimetals with the Fermi energy close to a quadratic band touching point. In particular, in order to address recent experiments on the spectroscopy of Pyrochlore Iridates and half-Heusler superconductors, we derive expressions for the optica...
1812.07555v2
2018-12-29
Magnetization flip in Fe-Cr-Ga system
A systematic investigation about the structure and magnetism of Fe75-xCr25Gax (11<x<33) and Fe50Cr50-yGay (0<y<33) series has been carried out in this work. It shows that the parent Fe50Cr25Ga25 phase has higher tolerance for Ga replacing Cr than replacing Fe atoms. An abrupt flip of Curie temperature and magnetization...
1812.11304v1
2020-05-07
Exchange-correlation corrections for electronic properties of half-metallic Co$_2$FeSi and nonmagnetic semiconductor CoFeTiAl
We consider two cobalt-based full-Heusler compounds CoFeTiAl and Co$_2$FeSi, for which Coulomb correlation effects play an important role. Since the standard GGA scheme does not provide a precise description of the electronic properties near the Fermi level, we use a meta-GGA functional capable to improve the descripti...
2005.03383v1
2020-05-29
Superconducting and Antiferromagnetic Properties of Dual-Phase V$_3$Ga
The binary compound V$_3$Ga can exhibit two near-equilibrium phases, consisting of the A15 structure that is superconducting, and the Heusler D0$_3$ structure that is semiconducting and antiferromagnetic. Density functional theory calculations show that the two phases are closely degenerate, being separated by only ~10...
2005.14348v1
2020-08-04
Ultra-High Thermoelectric Power Factors in Narrow Gap Materials with Asymmetric Bands
We theoretically unveil the unconventional possibility to achieve extremely high thermoelectric power factors in lightly doped narrow gap semiconductors with asymmetric conduction/valence bands operated in the bipolar transport regime. Specifically, using Boltzmann transport simulations, we show that narrow bandgap mat...
2008.01359v1
2020-08-26
Field-induced magnetic phase transitions and the resultant giant anomalous Hall effect in antiferromagnetic half-Heusler DyPtBi
We report field-induced magnetic phase transitions and transport properties of antiferromagnetic DyPtBi. We show that DyPtBi hosts a delicate balance between two different magnetic ground states, which can be controlled by a moderate magnetic field. Furthermore, it exhibits giant anomalous Hall effect (\sigma_A=1540 (o...
2008.11345v1
2021-03-15
Tuneable local order in thermoelectric crystals
Although crystalline solids are characterized by their periodic structures, some are only periodic on average and deviate on a local scale. Distinct local orderings can exist with identical periodic structures making their differences hidden to normal diffraction methods. Using x-ray scattering we investigate the therm...
2103.08543v1
2017-06-01
Materials Screening for the Discovery of New Half-Heuslers: Machine Learning versus Ab Initio Methods
Machine learning (ML) is increasingly becoming a helpful tool in the search for novel functional compounds. Here we use classification via random forests to predict the stability of half-Heusler (HH) compounds, using only experimentally reported compounds as a training set. Cross-validation yields an excellent agreemen...
1706.00192v1
2017-10-25
Site occupancy, composition and magnetic structure dependencies of martensitic transformation in Mn$_{2}$Ni$_{1+x}$Sn$_{1-x}$
A delicate balance between various factors such as site occupancy, composition and magnetic ordering seems to affect the stability of the martensitic phase in Mn$_{2}$Ni$_{1+x}$Sn$_{1-x}$. Using first-principles DFT calculations, we explore the impacts of each one of these factors on the martensitic stability of this s...
1710.09093v1
2018-04-09
Canted antiferromagnetism in phase-pure CuMnSb
We report the low-temperature properties of phase-pure single crystals of the half-Heusler compound CuMnSb grown by means of optical float-zoning. The magnetization, specific heat, electrical resistivity, and Hall effect of our single crystals exhibit an antiferromagnetic transition at $T_{\mathrm{N}} = 55~\mathrm{K}$ ...
1804.03223v1
2018-04-25
High $n$-type thermoelectric power factor and efficiency in Ba$_{2}$BiAu from a highly dispersive band
Using first-principles density-functional theory calculations, we predict the potential for unprecedented thermoelectric efficiency $zT=5$ at 800 K in $n$-type Ba$_{2}$BiAu full-Heusler compound. Such a high efficiency arises from an intrinsically ultralow lattice thermal conductivity coupled with a very high power fac...
1804.09392v2
2019-09-26
The study of magnetic topological semimetals by first principles calculations
Magnetic topological semimetals (TSMs) are topological quantum materials with broken time-reversal symmetry (TRS) and isolated nodal points or lines near the Fermi level. Their topological properties would typically reveal from the bulk-edge correspondence principle as nontrivial surface states such as Fermi arcs or dr...
1909.11999v1
2019-12-11
Chirality-induced linear response properties in non-coplanar Mn$_3$Ge
Taking the non-collinear antiferromagnetic hexagonal Heusler compound Mn$_3$Ge as a reference system, the contributions to linear response phenomena arising solely from the chiral coplanar and non-coplanar spin configurations are investigated. Orbital moments, X-ray absorption, anomalous and spin Hall effects, as well ...
1912.05211v1
2020-06-29
Spin-polarized Weyl cones and gigantic anomalous Nernst effect in ferromagnetic Heusler films
Weyl semimetals are characterized by the presence of massless band dispersion in momentum space. When a Weyl semimetal meets magnetism, large anomalous transport properties emerge as a consequence of its topological nature. Here, using $in-situ$ spin- and angle-resolved photoelectron spectroscopy combined with $ab\ ini...
2006.15769v2
2020-07-04
Impurities in 3D quadratic band-touching Luttinger semimetals : Friedel and RKKY oscillations
We investigate the response of 3D Luttinger semimetals to localized charge and spin impurities as a function of doping. The strong spin-orbit coupling of these materials strongly influences the Friedel oscillations and RKKY interactions. This can be seen at short distances with an $1/r^4$ divergence of the responses, a...
2007.02046v2
2020-09-01
Molecular beam epitaxy of the half-Heusler antiferromagnet CuMnSb
We report growth of CuMnSb thin films by molecular beam epitaxy on InAs(001) substrates. The CuMnSb layers are compressively strained ($0.6~\text{%}$) due to lattice mismatch. The thin films have a $\omega$ full width half max of $7.7^{''}$ according to high resolution X-ray diffraction, and a root mean square roughnes...
2009.00342v1
2020-09-02
Accessing the Single-Particle Structure of the Pygmy Dipole Resonance in $^{208}$Pb
New experimental data on the neutron single-particle character of the Pygmy Dipole Resonance (PDR) in $^{208}$Pb are presented. They were obtained from $(d,p)$ and resonant proton scattering experiments performed at the Q3D spectrograph of the Maier-Leibnitz Laboratory in Garching, Germany. The new data are compared to...
2009.01151v1
2020-11-13
Large anomalous Hall angle in a topological semimetal candidate TbPtBi
The magnetotransport properties in antiferromagnetic half-Heusler single crystals of TbPtBi, a magnetic-field-induced topological semimetal with simple band structure, are investigated. We found that a nonmonotonic magnetic field dependence of the anomalous Hall resistivity in a high magnetic field (B>7T), which come f...
2011.06864v1
2020-12-01
Nanocontact vortex oscillators based on Co$_2$MnGe pseudo-spin valves
We present an experimental study of vortex dynamics in magnetic nanocontacts based on pseudo spin valves comprising the Co$_2$MnGe Heusler compound. The films were grown by molecular beam epitaxy, where precise stoichiometry control and tailored stacking order allowed us to define the bottom ferromagnetic layer as the ...
2012.00522v3
2020-12-04
Growth, strain and spin orbit torques in epitaxial NiMnSb films sputtered on GaAs
We report current-induced spin torques in epitaxial NiMnSb films on a commercially available epi-ready GaAs substrate. The NiMnSb was grown by co-sputtering from three targets using optimised parameter. The films were processed into micro-scale bars to perform current-induced spin-torque measurements. Magnetic dynamics...
2012.02568v4
2020-12-11
Absence of superconductivity in topological metal ScInAu$_2$
The Heusler compound ScInAu$_2$ was previously reported to have a superconducting ground state with a critical temperature of 3.0 K. Recent high throughput calculations have also predicted that the material harbors a topologically non-trivial band structure similar to that reported for beta-PdBi$_2$. In an effort to ex...
2012.06501v1
2020-12-12
Ultra-fast Double Pulse All-Optical Re-switching of a Ferrimagnet
All-optical re-switching has been investigated in the half-metallic Heusler ferrimagnet Mn2Ru0.9Ga, where Mn atoms occupy two inequivalent sites in the XA-type structure. The effect of a second 200 fs 800 nm pump pulse that follows a first pulse, when both are above the threshold for switching, is studied as a function...
2012.06823v1
2020-12-29
Magnetotransport signatures of chiral magnetic anomaly in the half-Heusler phase ScPtBi
Study of magnetotransport properties of ScPtBi revealed simultaneously: a negative contribution to the longitudinal magnetoresistance, the planar Hall effect, and distinct angular narrowing of the longitudinal magnetoresistance { three hallmarks of chiral magnetic anomaly (pumping of axial charge between Weyl nodes), a...
2012.14819v2
2021-06-03
Quaternary-digital data storage based on magnetic bubbles in anisotropic materials
The topologically non-trivial nano-whirls, called magnetic skyrmions, are often considered attractive for spintronic applications like the racetrack data storage device. However, skyrmions do not move parallel to applied currents and typically do not coexist with other nano-objects, making the realization of such stora...
2106.01747v2
2021-06-24
Structure and magnetism in Fe-doped FeVSb and epitaxial Fe/FeVSb nanocomposite films
The combination of ferromagnetism and semiconducting behavior offers an avenue for realizing novel spintronics and spin-enhanced thermoelectrics. Here we demonstrate the synthesis of doped and nanocomposite half Heusler Fe$_{1+x}$VSb films by molecular beam epitaxy. For dilute excess Fe ($x < 0.1$), we observe a decrea...
2106.13165v1
2022-05-17
Cubic magneto-optic Kerr effect in Ni(111) thin films with and without twinning
In most studies utilizing the magneto-optic Kerr effect (MOKE), the detected change of polarized light upon reflection from a magnetized sample is supposed to be proportional to the magnetization $\boldsymbol{M}$. However, MOKE signatures quadratic in $\boldsymbol{M}$ have also been identified and utilized, e.g., to se...
2205.08298v2
2022-09-10
First-principles analysis of intravalley and intervalley electron-phonon scattering in thermoelectric materials
Intervalley collisions, which scatter electrons from one valley or band to another, can be detrimental to thermoelectric performance in materials with multiple valleys/bands. In this study, density functional theory is used to investigate the electron-phonon scattering characteristics of three lead chalcogenides (PbS, ...
2209.04659v1
2022-11-14
Coactive-Staggered Feature in Weyl Materials for Enhancing the Anomalous Nernst Conductivity
Power generation through the anomalous Nernst effect in topological Weyl materials has several advantages over conventional thermoelectrics due to the transverse geometry. However, the magnitude of the anomalous Nernst conductivity (ANC) in most known materials is too small to be of practical use, and there exist few g...
2211.07773v1
2022-12-09
Modelling assisted tunneling on the Bloch sphere using the Quantum Composer
The Bloch sphere representation is a geometric model for all possible quantum states of a two-level system that can be used to describe the time dynamics of a qubit. As explicit application, we consider the time dynamics of a particle in a double-well potential. In particular, we adopt a recent method for off-resonant ...
2212.04845v3
2022-12-31
An implementation of the density functional perturbation theory in the PAW framework
Quantifying materials' dynamical responses to external electromagnetic fields is central to understanding their physical properties. Here we present an implementation of the density functional perturbation theory for the computation of linear susceptibilities using the projector augmented-wave method. The Sternheimer e...
2301.00143v1
2023-02-14
Perspective: strain and strain gradient engineering in membranes of quantum materials
Strain is powerful for discovery and manipulation of new phases of matter; however, the elastic strains accessible to epitaxial films and bulk crystals are typically limited to small ($<2\%$), uniform, and often discrete values. This Perspective highlights new directions for strain and strain gradient engineering in fr...
2302.07390v1
2023-12-14
Defect formation energy, electronic structure and phonon dispersion study of half-Heusler TiSnX (X = Pd, Pt and Ni): an ab initio approach
In order to obtain reliable and close to the experimental transport properties, it is necessary to have a good description of the structural, electronic and vibrational properties of the materials. In this regard, the defect formation plays a crucial hole, specially when it has a small formation energy. In this study w...
2312.09186v1
2024-02-28
Symmetry-breaking normal state response and surface superconductivity in topological semimetal YPtBi
Most of the half-Heusler RPtBi compounds (R=rare earth) host various surface states due to spin-orbit coupling driven topological band structure. While recent ARPES measurements ubiquitously reported the existence of surface states in RPtBi, their evidence by other experimental techniques remains elusive. Here we repor...
2402.18735v1
2000-01-07
^{27}Al Impurity-Satellite NMR and Non-Fermi-Liquid Behavior in U_{1-x}Th_xPd_2Al_3
Non-Fermi-liquid (NFL) behavior in the f-sublattice-diluted alloy system U_{1-x}Th_xPd_2Al_3 has been studied using ^{27}Al nuclear magnetic resonance (NMR). Impurity satellites due to specific U near-neighbor configurations to ^{27}Al sites are clearly resolved in both random and field-aligned powder samples. The spat...
0001078v1
2000-05-23
Systematic study of Ga$_{1-x}$In$_x$As self-assembled quantum wires with different interfacial strain relaxation
A systematic theoretical study of the electronic and optical properties of Ga$_{1-x}$In$_x$As self-assembled quantum-wires (QWR's) made of short-period superlattices (SPS) with strain-induced lateral ordering is presented. The theory is based on the effective bond-orbital model (EBOM) combined with a valence-force fiel...
0005392v1
2003-03-10
Nitrogen local electronic structure in Ga(In)AsN alloys by soft-X-ray absorption and emission: Implications for optical properties
Soft-X-ray emission and absorption spectroscopies with their elemental specificity are used to determine the local electronic structure of N atoms in Ga(In)AsN diluted semiconductor alloys (N concentrations about 3%) in view of applications of such materials in optoelectronics. Deviations of the N local electronic stru...
0303163v3
2003-11-25
Evolution of Superconductivity and Charge Density Wave Ordering in the Lu$_5$Ir$_4$(Si$_{1-x}$Ge$_x$)$_{10}$ Alloy System
The compounds Lu$_5$Ir$_4$Si$_{10}$ and Lu$_5$Ir$_4$Ge$_{10}$ crystallize in the tetragonal Sc$_5$Co$_4$Si$_{10}$ type structure. Lu$_5$Ir$_4$Si$_{10}$ is known to superconduct below 3.9 K and it also exhibits a strongly coupled charge density wave (CDW) transition below 83 K. Lu$_5$Ir$_4$Ge$_{10}$ undergoes a transiti...
0311590v1
2004-04-07
Quantitative Phase Field Model of Alloy Solidification
We present a detailed derivation and thin interface analysis of a phase-field model that can accurately simulate microstructural pattern formation for low-speed directional solidification of a dilute binary alloy. This advance with respect to previous phase-field models is achieved by the addition of a phenomenological...
0404164v2
2005-08-24
Compositional disorder and its influence on the structural, electronic and magnetic properties of MgC(Ni_{1-x}Co_{x})_{3} alloys using first-principles
First-principles, density-functional based electronic structure calculations are carried out for MgC(Ni_{1-x}Co_{x})_{3} alloys over the concentration range 0\leq x\leq1, using Korringa-Kohn-Rostoker coherent-potential approximation (KKR CPA) method in the atomic sphere approximation (ASA). The self-consistent calculat...
0508569v2
2006-01-25
The wave model of martensite growth for the FCC-BCC transformation of iron-based alloys
This book is the first monograph in the scientific literature, dedicated to the FCC-BCC transformation in iron-based alloys, in which the dynamical approach is used for the explanation of the martensite growth stage. The rapid growth of a cooling martensite crystal is considered as a self-organized process controlled...
0601569v4
2006-04-14
Phonons in disordered alloys : a multiple scattering approach
In this paper we shall discuss the effect of disorder induced configuration fluctuations on single particle and two-particle phonon Green functions in substitutional random binary alloys. The randomness of the system will be dealt within the augmented space theorem, introduced by one of us [J. Phys. C : Solid State Phy...
0604373v2
2006-05-09
Interplay of order-disorder phenomena and diffusion in rigid binary alloys: Monte Carlo simulations of the two-dimensional ABV model
Transport phenomena are studied for a binary (AB) alloy on a rigid square lattice with nearest-neighbor attraction between unlike particles, assuming a small concentration $c_v$ of vacancies $V$ being present, to which $A(B)$ particles can jump with rates $\Gamma_A (\Gamma_B)$ in the case where the nearest neighbor att...
0605241v1
2006-07-14
High-dielectric constant and wide band gap inverse silver oxide phases of the ordered ternary alloys of SiO$_{2}$, GeO$_{2}$ and SnO$_{2}$
High-dielectric constant and wide band gap oxides have important technological applications. The crystalline oxide polymorphs having lattice constant compatibility to silicon are particularly desirable. One recently reported candidate is the inverse silver oxide phase of SiO$_2$. First-principles study of this system t...
0607353v2
2006-08-02
Solid-Liquid Phase Diagrams for Binary Metallic Alloys: Adjustable Interatomic Potentials
We develop a new approach to determining LJ-EAM potentials for alloys and use these to determine the solid-liquid phase diagrams for binary metallic alloys using Kofke's Gibbs-Duhem integration technique combined with semigrand canonical Monte Carlo simulations. We demonstrate that it is possible to produce a wide-rang...
0608039v3
2006-09-21
Evolution of ferromagnetic order in URhGe alloyed with Ru, Co and Si
We have investigated the evolution of ferromagnetic order in the correlated metal URhGe (Curie temperature $T_{\rm C} = $9.5 K) by chemical substitution of Ru, Co and Si. Polycrystalline samples URh$_{1-x}$Ru$_x$Ge ($x \leq $0.6), URh$_{1-x}$Co$_x$Ge ($x \leq $0.9) and URhGe$_{1-x}$Si$_x$ ($x \leq $0.2) have been prepa...
0609557v2
2006-10-25
Spontaneous ordering as an intrinsic effect at the mesoscopic scale: A vibrational insight in (Zn,Be)Se by Raman scattering and first-principles calculations
The recent finding of a 1-bond->2-phonon `percolation'-type behaviour in several random zincblende alloys, supporting an unsuspected 1-bond->2-mode behaviour in the bond length distribution, renews interest for a discussion of CuPt-type spontaneous ordering (CPSO) as a purely intrinsic effect. We investigate this key i...
0610682v3
2007-01-26
Quantum transport in quasicrystals and complex metallic alloys
The semi-classical Bloch-Boltzmann theory is at the heart of our understanding of conduction in solids, ranging from metals to semi-conductors. Physical systems that are beyond the range of applicability of this theory are thus of fundamental interest. This is the case of disordered systems which present quantum interf...
0701639v1
2008-01-22
Impurity modes and effect of clustering in diluted semiconductor alloys
The variation of TO zone-center vibration spectra with concentration in mixed zincblende-type semiconductors can be understood within a paradigm of unified "one bond - two modes" approach, which has been recently outlined as a rather general concept, and emerges from a number of previous experimental and theoretical st...
0801.3419v1
2009-01-09
Experimental study of high energy electron interactions in a superconducting aluminum alloy resonant bar
Peak amplitude measurements of the fundamental mode of oscillation of a suspended aluminum alloy bar hit by an electron beam show that the amplitude is enhanced by a factor ~3.5 when the material is in the superconducting state. This result is consistent with the cosmic ray observations made by the resonant gravitation...
0901.1220v1
2009-02-17
First-principle solubilities of alkali and alkaline earth metals in Mg-B alloys
By devising a novel framework, we present a comprehensive theoretical study of solubilities of alkali (Li, Na, K, Rb, Cs) and alkaline earth (Be, Ca, Sr, Ba) metals in the he boron-rich Mg-B system. The study is based on first-principle calculations of solutes formation energies in MgB$_2$, MgB$_4$, MgB$_7$ alloys and ...
0902.2958v1
2009-10-14
Debye temperature of disordered bcc-Fe-Cr alloys
Debye temperature, TD, of Fe100-xCrx disordered alloys with 0<x<99.9 was determined from the temperature dependence of the centre shift of 57Fe Mossbauer spectra recorded in the temperature range of 80-300K. Its compositional dependence shows an interesting non-monotonous behaviour. For 0<x<~45 as well as for ~75<x<~95...
0910.2544v1
2010-09-14
Composite THz materials using aligned metallic and semiconductor microwires, experiments and interpretation
We report fabrication method and THz characterization of composite films containing either aligned metallic (tin alloy) microwires or chalcogenide As2Se3 microwires. The microwire arrays are made by stack-and-draw fiber fabrication technique using multi-step co-drawing of low-melting-temperature metals or semiconductor...
1009.2658v1
2011-01-01
Signature effects of spin clustering and distribution of spin couplings on magnetization behaviour in Ni-Fe-Mo and Ni-Fe-W alloys
The spontaneous magnetization as a function of temperature is investigated for a number of disordered Ni-Fe-Mo and Ni-Fe-W alloys using superconducting quantum interference device magnetometry, with a focus on the low-T behavior as well as the critical exponents associated with the magnetic phase transition. While the ...
1101.0343v2
2011-07-06
Factors controlling the energetics of the oxygen reduction reaction on the Pd-Co electro-catalysts: Insight from first principles
We report here results of our density functional theory based computational studies of the electronic structure of the Pd-Co alloy electrocatalysts and energetics of the oxygen reduction reaction (ORR) on their surfaces. The calculations have been performed for the (111) surfaces of pure Pd, Pd0.75Co0.25 and Pd0.5Co0.5...
1107.1231v1
2011-09-09
Study of ageing in Al-Mg-Si alloys by positron annihilation spectroscopy
In many common Al-Mg-Si alloys (6000 series) intermediate storage at or near 'room temperature' after solutionising leads to pronounced changes of the precipitation kinetics during the ensuing artificial ageing step at \approx 180{\deg}C. This is not only an annoyance in production, but also a challenge for researchers...
1109.2019v2
2011-09-26
Instability types at ion-assisted alloy deposition: from two-dimensional to three-dimensional nanopattern growth
Ion irradiation during film growth has a strong impact on structural properties. Linear stability analysis is employed to study surface instabilities during ion-assisted growth of binary alloys. An interplay between curvature-dependent ion-driven and deposition-driven instabilities is investigated. We demonstrate that ...
1109.5461v3