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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
2011-10-10
Ab-initio calculation of effective exchange interactions, spin waves, and Curie temperature in L2_1- and L1_2-type local moment ferromagnets
Employing first-principles electronic structure calculations in conjunction with the frozen-magnon method we study the effective exchange interactions and spin waves in local moment ferromagnets. As prototypes we have chosen three L2$_1$-type full Heusler alloys Cu$_2$MnAl, Ni$_2$MnSn and Pd$_2$MnSn, and the L1$_2$-typ...
1110.2156v1
2014-05-19
Low-Dimensional Transport and Large Thermoelectric Power Factors in Bulk Semiconductors by Band Engineering of Highly Directional Electronic States
Thermoelectrics are promising to address energy issues but their exploitation is still hampered by low efficiencies. So far, much improvement has been achieved by reducing the thermal conductivity but less by maximizing the power factor. The latter imposes apparently conflicting requirements on the band structure: a na...
1405.4685v3
2015-06-29
Giant magnetocaloric effect from reverse martensitic transformation in Ni-Mn-Ga-Cu ferromagnetic shape memory alloys
In an effort to produce Giant Magnetocaloric effect (GMCE) near room temperature, in a first ever such study, the austenite transformation temperature (As) was fine tuned to ferromagnetic Curie temperature (TC) in Ferromagnetic Shape Memory Alloys (FSMA) and a large GMCE of delta-SM = - 81.75 J/Kg-K was achieved in Ni5...
1506.08709v2
2018-05-16
Thermoelectric Alchemy: Designing A Chemical Analog to PbTe with Intrinsic High Band Degeneracy and Low Lattice Thermal Conductivity
Improving the figure of merit $zT$ of thermoelectric materials requires simultaneously a high power factor and low thermal conductivity. An effective approach for increasing the power factor is to align the band extremum and achieve high band degeneracy ($\geq$ 12) near the Fermi level as realized in PbTe [\textcolor{b...
1805.06433v1
2018-06-18
AFLOW-CHULL: Cloud-oriented platform for autonomous phase stability analysis
$\textit{A priori}$ prediction of phase stability of materials is a challenging practice, requiring knowledge of all energetically-competing structures at formation conditions. Large materials repositories $\unicode{x2014}$ housing properties of both experimental and hypothetical compounds $\unicode{x2014}$ offer a pat...
1806.06901v1
2018-09-19
Exploring the best scenario for understanding the high temperature thermoelectric behaviour of Fe2VAl
Heusler-type Fe2VAl compound is a promising thermoelectric candidate with non-magnetic ground state. The present work investigates the Seebeck coefficient (S) of Fe2VAl in the temperature region 300 to 620 K with the help of experimental and theoretical tools. The experimental value of S is observed -130 {\mu}V/K at 30...
1809.07015v1
2019-04-10
Non-trivial topological valence bands of common diamond and zinc-blende semiconductors
The diamond and zinc-blende semiconductors are well-known and have been widely studied for decades. Yet, their electronic structure still surprises with unexpected topological properties of the valence bands. In this joint theoretical and experimental investigation we demonstrate for the benchmark compounds InSb and Ga...
1904.05063v1
2016-03-03
Room-temperature magnetic topological semimetal state in half-metallic Heusler Co$_2$TiX (X=Si, Ge, or Sn)
Topological semimetals (TSMs) including Weyl semimetals and nodal-line semimetals are expected to open the next frontier of condensed matter and materials science. Although the first inversion breaking Weyl semimetal was recently discovered in TaAs, its magnetic counterparts, i.e., the time-reversal breaking Weyl and n...
1603.01255v3
2020-07-27
Role of magnetic exchange interactions in chiral-type Hall effects of epitaxial Mn$_{x}$PtSn films
Tetragonal Mn-based Heusler compounds feature rich exchange interactions and exotic topological magnetic textures, such as antiskyrmions, complimented by the chiral-type Hall effects. This makes the material class interesting for device applications. We report the relation of the magnetic exchange interactions to the t...
2007.13412v1
2022-04-19
Thermoelectric properties of Fe$_{2}$VAl at high temperature region: A combined experimental and theoretical study
Heusler type compounds have long been recognized as potential thermoelectric (TE) materials. Here, the experimentally observed TE properties of Fe$_{2}$VAl are understood through electronic structure calculations in the temperature range of $300-800$ K. The observed value of $S$ is $\sim-$138 $\mu$V/K at 300 K. Then, t...
2204.08654v1
2005-04-20
First-principles study of thin magnetic transition-metal silicide films on Si(001)
In order to combine silicon technology with the functionality of magnetic systems, a number of ferromagnetic (FM) materials have been suggested for the fabrication of metal/semiconductor heterojunctions. In this work, we present a systematic study of several candidate materials in contact with the Si surface. We employ...
0504515v2
2017-08-25
Topological superconductivity of spin-3/2 carriers in a three-dimensional doped Luttinger semimetal
We investigate topological Cooper pairing, including gapless Weyl and fully gapped class DIII superconductivity, in a three-dimensional doped Luttinger semimetal. The latter describes effective spin-3/2 carriers near a quadratic band touching and captures the normal-state properties of the 227 pyrochlore iridates and h...
1708.07825v2
2019-07-05
Thermoelectric transport trends in group 4 half-Heusler alloys
The thermoelectric properties of 54 different group 4 half-Heusler (HH) alloys have been studied from first principles. Electronic transport was studied with density functional theory using hybrid functionals facilitated by the $\mathbf{k} \cdot \mathbf{p}$ method, while the temperature dependent effective potential me...
1907.02845v1
2021-11-02
Microstructure engineering of metamagnetic Ni-Mn-based Heusler compounds by Fe-doping: A roadmap towards excellent cyclic stability combined with large elastocaloric and magnetocaloric effects
Ni-Mn-based metamagnetic shape-memory alloys exhibit a giant thermal response to magnetic fields and uniaxial stress which can be utilized in single caloric or multicaloric cooling concepts for energy-efficient and sustainable refrigeration. However, during cyclic operation these alloys suffer from structural and funct...
2111.01621v2
2022-06-22
Non-trivial topological phases in transition metal rich half-Heusler Oxides
Topological Insulators with gapless surface states and insulating bulk in non-centrosymmetric cubic systems have been extensively explored following the discovery of two-dimensional quantum spin hall effect in zincblende HgTe. In such systems the negative band inversion strength E$_{BIS}$ ($=$ E$_{\Gamma_6} -$ E$_{\Gam...
2206.10976v2
2023-09-14
Composition and Structure Based GGA Bandgap Prediction Using Machine Learning Approach
This study focuses on developing precise machine learning (ML) regression models for predicting energy bandgap values based on chemical compositions and crystal structures. The primary aim is to match the accuracy of predictions derived from GGA-PBE calculations and validate them through density functional theory (DFT)...
2309.07424v1
2011-06-24
Magnetic dichroism in angular-resolved hard X-ray photoelectron spectroscopy from buried layers
This work reports the measurement of magnetic dichroism in angular-resolved photoemission from in-plane magnetized buried thin films. The high bulk sensitivity of hard X-ray photoelectron spectroscopy (HAXPES) in combination with circularly polarized radiation enables the investigation of the magnetic properties of bur...
1106.4976v1
2012-01-30
Insights into the electronic structure of Co2FeSi from x-ray magnetic linear dichroism
Experimental evidence both for and against a half-metallic ground-state of the Heusler compound Co2FeSi has been published. Density functional theory based calculations suggest a non half-metallic ground state. It has been argued, that on-site Coulomb interaction of the d electrons has to be taken into account via the ...
1201.6263v2
2012-03-13
Stabilization of Majorana modes in vortices in the superconducting phase of topological insulators using topologically trivial bands
If superconductivity is induced in the metallic surface states of topological insulators via proximity, Majorana modes will be trapped on the vortex cores. The same effects hold for doped topological insulators which become bulk s-wave superconductors as long as the doping does not exceed a critical values $ \mu^{\pm}_...
1203.2958v2
2013-11-21
Effect of annealing on spinodally decomposed Co2CrAl grown via floating zone technique
Among the large class of Heusler compounds, Co2CrAl is predicted to be 100 % spin polarized and is hence, a potential candidate for application in spintronics. So far, the predicted properties have not been experimentally realized which may be attributed to the phase segregated nature of samples. This phase segregation...
1311.5453v1
2015-01-16
State of Co and Mn in half-metallic ferromagnet Co$_2$MnSi explored by magnetic circular dichroism in hard X-ray photoelectron emission and soft X-ray absorption spectroscopies
The half-metallic Heusler compound Co$_2$MnSi is a very attractive material for spintronic devices because it exhibits very high tunnelling magnetoresistance ratios. This work reports on a spectroscopic investigation of thin Co$_2$MnSi films as they are used as electrodes in magnetic tunnel junctions. The investigated ...
1501.03966v1
2016-11-28
Synthesis of low-moment CrVTiAl: a potential room temperature spin filter
The efficient production of spin-polarized currents at room temperature is fundamental to the advancement of spintronics. Spin-filter materials --- semiconductors with unequal band gaps for each spin channel --- can generate spin-polarized current without the need for spin-polarized contacts. In addition, a spin-filter...
1611.09307v3
2017-07-11
Unconventional Superconductivity in Luttinger Semimetals: Theory of Complex Tensor Order and the Emergence of the Uniaxial Nematic State
We investigate unconventional superconductivity in three-dimensional electronic systems with the chemical potential close to a quadratic band touching point in the band dispersion. Short-range interactions can lead to d-wave superconductivity, described by a complex tensor order parameter. We elucidate the general stru...
1707.03444v2
2017-11-30
Topological Hopf and chain link semimetal states and their application to Co2MnGa (Theory and Materials Prediction)
Topological semimetals can be classified by the connectivity and dimensionality of the band cross- ing in momentum space. The band crossings of a Dirac, Weyl, or an unconventional fermion semimet- al are 0D points, whereas the band crossings of a nodal-line semimetal are 1D closed loops. Here we propose that the presen...
1712.00055v1
2018-11-09
Topological d+s wave superconductors in a multi-orbital quadratic band touching system
Realization of topological superconductors is one of the most important goals in studies of topological phases in quantum materials. In this work, we theoretically propose a novel way to attain topological superconductors with non-trivial Fermi surfaces of Bogoliubov quasiparticles. Considering the interacting Luttinge...
1811.04046v1
2018-11-10
Magnetic Order and Lattice Instabilities in Ni$_{2}$Mn$_{1+x}$Sn$_{1-x}$ Heusler based Magnetic Shape-Memory Alloys
The magnetic correlations in the austenite phase and the consequent martensitic transition in inverse magnetocaloric alloys, Ni$_{2}$Mn$_{1+x}$Sn$_{1-x}$, have been a matter of debate for decades. We conclusively establish using {\it ab initio} phonon calculations that the spin alignment of excess Mn at the Sn site (Mn...
1811.04221v1
2018-11-12
Large anomalous Hall and Nernst effect from nodal line symmetry breaking in Fe$_2$MnX (X=P,As,Sb)
A large Berry curvature in the vicinity of the Fermi energy is required in order to obtain a large anomalous Hall and Nernst effect. This Berry curvature can be induced by Weyl points and gapped nodal lines. One of the possible mechanisms takes place in systems with a symmetry group where mirror planes lead to protecte...
1811.04680v1
2018-07-06
Strategic enhancement of anomalous Nernst effect in Co2MnAl1-xSix Heusler compounds
The anomalous Nernst effect (ANE), a thermoelectric phenomenon in magnetic materials, has potential for novel energy harvesting applications because its orthogonal relationship between the temperature gradient and the electric field enables us to utilize the large area of non-flat heat sources. In this study, the requi...
1807.02209v3
2018-07-17
Large anomalous Nernst effect in thin films of the Weyl semimetal Co2MnGa
The magneto-thermoelectric properties of Heusler compound thin films are very diverse. Here, we discuss the anomalous Nernst response of Co$_2$MnGa thin films. We systematically study the anomalous Nernst coefficient as a function of temperature, and we show that unlike the anomalous Hall effect, the anomalous Nernst e...
1807.06487v1
2018-07-20
Characterization of topological band structures away from the Fermi level by anomalous Nernst measurements
Resolving the structure of energy bands in transport experiments is a major challenge in condensed matter physics and material science. Sometimes, however, traditional electrical conductance or resistance measurements only provide very small signals, and thus limit the ability to obtain direct band structure informatio...
1807.07843v1
2019-04-02
Spin pumping and spin torque in interfacial tailored Co2FeAl/\b{eta}-Ta layers
The Heusler ferromagnetic (FM) compound Co2FeAl interfaced with a high-spin orbit coupling non-magnetic (NM) layer is a promising candidate for energy efficient spin logic circuits. The circuit potential depends on the strength of angular momentum transfer across the FM/NM interface; hence, requiring low spin memory lo...
1904.01506v3
2022-03-04
In-situ nitriding of Fe2VAl during laser surface remelting to manipulate microstructure and crystalline defects
Tailoring the physical properties of complex materials for targeted applications requires optimizing the microstructure and crystalline defects that influence electrical and thermal transport, and mechanical properties. Laser surface remelting can be used to modify the sub-surface microstructure of bulk materials and h...
2203.02209v1
2019-05-24
A first-principles investigation of Topological Phase Transition in face-centred cubic LiMgBi
Topological Insulators (TI) exhibit robust spin-locked dissipationless Fermion transport along the surface states. In the current study, we use \textit{first-principles} calculations to investigate a Topological Phase Transition (TPT) in a Half-Heusler (HH) compound LiMgBi driven by a Volume Expansive Pressure (VEP) wh...
1905.10103v2
2019-09-04
Exploring Disorder in the Spin Gapless Semiconductor Mn$_2$CoAl
Since the prediction of spin-gapless semiconducting behaviour in the Heusler compound Mn$_2$CoAl, evidence of spin-gapless behaviour in thin films has typically been inferred from magnetotransport measurements. The spin gapless state is however fragile, and further, band structure calculations indicate that even a smal...
1909.02153v1
2019-12-13
Shallow impurity band in ZrNiSn
ZrNiSn and related half Heusler compounds are candidate materials for efficient thermoelectric energy conversion with a reported thermoelectric figure-of-merit of n-type ZrNiSn exceeding unity. Progress on p-type materials has been more limited, which has been attributed to the presence of an impurity band, possibly re...
1912.06539v1
2020-06-04
Material Descriptors for the Discovery of Efficient Thermoelectrics
The predictive performance screening of novel compounds can significantly promote the discovery of efficient, cheap, and non-toxic thermoelectric materials. Large efforts to implement machine-learning techniques coupled to materials databases are currently being undertaken, but the adopted computational methods can dra...
2006.02789v2
2021-01-29
Room-temperature antiskyrmions and sawtooth surface textures in a noncentrosymmetric magnet with $S_4$ symmetry
Topological spin textures have attracted much attention both for fundamental physics and spintronics applications. Among them, antiskyrmions possess a unique spin configuration with Bloch-type and N\'eel-type domain walls due to anisotropic Dzyaloshinskii-Moriya interaction (DMI) in the noncentrosymmetric crystal struc...
2101.12359v1
2021-10-11
Absolute calibration of the latent heat of transition using differential thermal analysis
We describe a simple and accurate differential thermal analysis set up to measure the latent heat of solid state materials undergoing abrupt phase transitions in the temperature range from 77 K to above room temperature. We report a numerical technique for the absolute calibration of the latent heat of the transition, ...
2110.05046v1
2021-11-20
Skyrmionics in correlated oxides
While chiral magnets, metal-based magnetic multilayers, or Heusler compounds have been considered as the material workhorses in the field of skyrmionics, oxides are now emerging as promising alternatives, as they host special correlations between the spin-orbital-charge-lattice degrees of freedom and/or coupled ferroic...
2111.10562v2
2021-11-28
CoFeVSb: A Promising Candidate for Spin Valve and Thermoelectric Applications
We report a combined theoretical and experimental study of a novel quaternary Heusler system CoFeVSb from the view point of room temperature spintronics and thermoelectric applications. It crystallizes in cubic structure with small DO$_3$-type disorder. The presence of disorder is confirmed by room temperature synchrot...
2111.14081v1
2022-06-06
Quantitative theory of magnetic interactions in solids
In this report we review the method of explicit calculations of interatomic exchange interactions of magnetic materials. This involves exchange mechanisms normally referred to as Heisenberg exchange, Dzyaloshinskii-Moriya interaction and anisotropic symmetric exchange. The connection between microscopic theories of the...
2206.02415v2
2022-08-24
The type-I antiferromagnetic Weyl semimetal InMnTi$_2$
Topological materials have been a main focus of studies in the past decade due to their protected properties that can be exploited for the fabrication of new devices. Among them, Weyl semimetals are a class of topological semimetals with non-trivial linear band crossing close to the Fermi level. The existence of such c...
2208.11412v3
2022-12-05
Quantifying nonadiabaticity in major families of superconductors
The classical Bardeen-Cooper-Schrieffer and Eliashberg theories of the electron-phonon-mediated superconductivity are based on the Migdal theorem, which is an assumption that the energy of charge carriers, $k{_B}T{_F}$, significantly exceeds the phononic energy, $\hbar{\omega{_D}} $, of the crystalline lattice. This as...
2212.02396v3
2023-01-13
Spin and current transport in the robust half-metallic magnet $c$-CoFeGe
Spintronics is an emerging form of electronics based on the electrons' spin degree of freedom for which materials with robust half-metallic ferromagnet (HMF) character are very attractive. Here we determine the structural stability, electronic, magnetic, and mechanical properties of the half-Heusler (hH) compound CoFeG...
2301.05493v1
2022-08-07
A machine learning approach to predict the structural and magnetic properties of Heusler alloy families
Random forest (RF) regression model is used to predict the lattice constant, magnetic moment and formation energies of full Heusler alloys, half Heusler alloys, inverse Heusler alloys and quaternary Heusler alloys based on existing as well as indigenously prepared databases. Prior analysis was carried out to check the ...
2208.12705v1
2007-11-15
Characterization of half-metallic L2_1-phase Co_2FeSi full-Heusler alloy films formed by rapid thermal annealing
The authors developed a preparation technique of Co_2FeSi full-Heusler alloy films with the L2_1-ordered structure on silicon-on-insulator (SOI) substrates, employing rapid thermal annealing (RTA). The Co_2FeSi full-Heusler alloy films were successfully formed by RTA-induced silicidation reaction between an ultrathin S...
0711.2404v1
2013-01-25
All-Heusler giant-magnetoresistance junctions with matched energy bands and Fermi surfaces
We present an all-Heusler architecture which could be used as a rational design scheme for achieving high spin-filtering efficiency in the current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices. A Co2MnSi/Ni2NiSi/Co2MnSi trilayer stack is chosen as the prototype of such an architecture, of which the e...
1301.6106v1
2017-04-05
Structure, site-specific magnetism and magneto-transport properties of epitaxial D0$_{22}$ Mn$_2$Fe$_x$Ga thin films
Ferrimagnetic Mn$_2$Fe$_x$Ga $(0.26 \leq x \leq 1.12)$ thin films have been characterised by X-ray diffraction, SQUID magnetometry, X-ray absorption spectroscopy, X-ray magnetic circular dichroism and M\"{o}ssbauer spectroscopy with the aim of determining the structure and site-specific magnetism of this tetragonal, D0...
1704.01326v1
2021-06-22
Superconductivity in spin-$3/2$ systems: symmetry classification, odd-frequency pairs, and Bogoliubov Fermi surfaces
The possible symmetries of the superconducting pair amplitude is a consequence of the fermionic nature of the Cooper pairs. For spin-$1/2$ systems this leads to the $\mathcal{SPOT}=-1$ classification of superconductivity, where $\mathcal{S}$, $\mathcal{P}$, $\mathcal{O}$, and $\mathcal{T}$ refer to the exchange operato...
2106.11983v2
2021-10-26
Spin- and time-resolved photoelectron spectroscopy and diffraction studies using time-of-flight momentum microscopes
Momentum microscopy (MM) is a novel way of performing angular-resolved photoelectron spectroscopy (ARPES). Combined with time-of-flight (ToF) energy recording, its high degree of parallelization is advantageous for photon-hungry experiments like ARPES at X-ray energies and spin-resolved ARPES. This article introduces i...
2110.13832v2
2022-11-25
Two-band conduction as a pathway to non-linear Hall effect and unsaturated negative magnetoresistance in the martensitic compound GdPd2Bi
The present work aims to address the electronic and magnetic properties of the intermetallic compound GdPd$_2$Bi through a comprehensive study of the structural, magnetic, electrical and thermal transport on a polycrystalline sample, followed by theoretical calculations. Our findings indicate that the magnetic ground s...
2211.13982v1
2019-10-29
Perpendicular magnetic anisotropy in Pt/Co-based full Heusler alloy/MgO thin films structures
Perpendicular magnetic anisotropy (PMA) in ultrathin magnetic structures is a key ingredient for the development of electrically controlled spintronic devices. Due to their relatively large spin-polarization, high Curie temperature and low Gilbert damping the Co-based full Heusler alloys are of special importance from ...
1910.13107v1
2009-01-12
Screening and Fabrication of Half-Heusler phases for thermoelectric applications
Half-Heusler phases have gained recently much interest as thermoelectric materials. Screening of possible systems was performed by ab-initio simulation using VASP-software. The energy-versus-Volume (E(V)) curves were calculated and calibrated. For TiCoSb, NbNiSn, FeMoSb the stability of Half-Heusler phase against concu...
0901.1491v3
2015-07-21
Realization of multifunctional shape-memory ferromagnets in all-d-metal Heusler phases
Heusler ferromagnetic shape-memory alloys (FSMAs) normally consist of transition-group d-metals and main-group p-elements. Here, we report the realization of FSMAs in Heusler phases that completely consist of d metals. By introducing the d-metal Ti into NiMn alloys, cubic B2-type Heusler phase is obtained and the marte...
1507.05907v1
2016-08-10
Equiatomic quaternary Heusler alloys: a material perspective for spintronic applications
Half-metallic ferromagnetic (HMF) materials show high spin polarization and are therefore interesting to researchers due to their possible applications in spintronic devices. In these materials, while one spin sub band has a finite density of states at the Fermi level, the other sub band has a gap. Because of their hig...
1608.03088v1
2002-09-24
On Order-Disorder ($L2_1 \to B2^\prime$) Phase Transition in Ni$_{2+x}Mn_{1-x}$Ga Heusler Alloys
Order-disorder phase transition in Ni$_{2+x}Mn_{1-x}$Ga Heusler alloys has been studied. It was found that the $L2_1 \to B2^{\prime}$ phase transition in Ni2+xMn1-xGa (x = 0.16 - 0.20) Heusler alloys is of second order and the temperature of this transition decreases with Ni excess.
0209547v1
2011-03-30
The efficient spin injector scheme based on Heusler materials
We present the rational design scheme intended to provide the stable high spin-polarization at the interfaces of the magneto-resistive junctions by fulfilling the criteria of structural and chemical compatibilities at the interface. This can be realized by joining the semiconducting and half-metallic Heusler materials ...
1103.5928v1
2015-01-16
A first-principle study on some quanternary Heusler alloys with 4d and 3d transition metal elements
In this letter, we investigate the magnetic properties, electronic structures, Slater-Pauling behaviours of some quanternary Heusler alloys with 4d and 3d transition metal elements. The energy levels of the minority-spin electronic band structures for all our calculated alloys are discussed. We have summaried 21 quante...
1501.03871v1
2017-03-24
Probing the degree of spin polarization of a ferromagnet with ferromagnet/superconductor proximity effect
Superconductor/ferromagnet proximity effect has been studied for Pb/Co$_2$Cr$_{1-x}$Fe$_x$Al bilayers. Different substrate temperatures allowed us to prepare the Heusler alloy Co$_2$Cr$_{1-x}$Fe$_x$Al films with different degree of spin polarization of conduction band of the Heusler layer. We obtain a strong correlatio...
1703.08422v1
2012-02-17
Insights into ultrafast demagnetization in pseudo-gap half metals
Interest in femtosecond demagnetization experiments was sparked by Bigot's discovery in 1995. These experiments unveil the elementary mechanisms coupling the electrons' temperature to their spin order. Even though first quantitative models describing ultrafast demagnetization have just been published within the past ye...
1202.3874v1
2015-10-12
Room-temperature spin-orbit torque in NiMnSb
Materials that crystalize in diamond-related lattices, with Si and GaAs as their prime examples, are at the foundation of modern electronics. Simultaneoulsy, the two atomic sites in the unit cell of these crystals form inversion partners which gives rise to relativistic non-equilibrium spin phenomena highly relevant fo...
1510.03356v1
2016-11-14
Phase diagram of electronic systems with quadratic Fermi nodes in $2<d<4$: $2+ε$ expansion, $4-ε$ expansion, and functional renormalization group
Several materials in the regime of strong spin-orbit interaction such as HgTe, the pyrochlore iridate Pr$_2$Ir$_2$O$_7$, and the half-Heusler compound LaPtBi, as well as various systems related to these three prototype materials, are believed to host a quadratic band touching point at the Fermi level. Recently, it has ...
1611.04594v2
2017-07-12
Superconductivity in three-dimensional spin-orbit coupled semimetals
Motivated by the experimental detection of superconductivity in the low-carrier density half-Heusler compound YPtBi, we study the pairing instabilities of three-dimensional strongly spin-orbit coupled semimetals with a quadratic band touching point. In these semimetals the electronic structure at the Fermi energy is de...
1707.03831v2
2018-01-06
Development of half metallicity within mixed magnetic phase of Cu$_{1-x}$Co$_x$MnSb alloy
Cubic Half-Heusler Cu$_{1-x}$Co$_x$MnSb (0 $\leq$ $x$ $\leq$ 0.1) compounds have been investigated both experimentally and theoretically for their magnetic, transport and electronic properties in search of possible half metallic antiferromagnetism. The systems (Cu,Co)MnSb are of particular interest as the end member al...
1801.02035v1
2020-09-02
New highly-anisotropic Rh-based Heusler compound for magnetic recording
The development of high-density magnetic recording media is limited by the superparamagnetism in very small ferromagnetic crystals. Hard magnetic materials with strong perpendicular anisotropy offer stability and high recording density. To overcome the difficulty of writing media with a large coercivity, heat assisted ...
2009.01034v1
2021-11-04
Influence of microstructure on the application of Ni-Mn-In Heusler compounds for multicaloric cooling using magnetic field and uniaxial stress
Novel multicaloric cooling utilizing the giant caloric response of Ni-Mn-based metamagnetic shape-memory alloys to different external stimuli such as magnetic field, uniaxial stress and hydrostatic pressure is a promising candidate for energy-efficient and environmentally-friendly refrigeration. However, the role of mi...
2111.03092v2
2022-07-12
First-principles study of optoelectronic and thermoelectronic properties of the ScAgC half-Heusler compound
This work presents a theoretical study regarding photovoltaic (PV) & thermoelectric (TE) applications of ScAgC. The electronic, optical and thermoelectric properties are investigated using DFT and semi-classical Boltzmann transport theory. DFT calculates a direct band-gap of $\sim$$0.47$ eV, while $G_{0}W_{0}$ method e...
2207.05661v2
2022-09-30
Coexisting structural disorder and robust spin-polarization in half-metallic FeMnVAl
Half-metallic ferromagnets (HMF) are on one of the most promising materials in the field of spintronics due to their unique band structure consisting of one spin sub-band having metallic characteristics along with another sub-band with semiconductor-like behavior. In this work, we report the synthesis of a novel quater...
2209.15243v1
2022-10-09
High-performance non-Fermi-liquid metallic thermoelectric materials
Searching for high-performance thermoelectric (TE) materials in the paradigm of narrow-bandgap semiconductors has lasted for nearly 70 years and is obviously hampered by a bottleneck of research now. Here we report on the discovery of a few metallic compounds, TiFexCu2x-1Sb and TiFe1.33Sb, showing the thermopower excee...
2210.04201v1
2023-01-03
Surprisingly large anomalous Hall effect and giant negative magnetoresistance in half-topological semimetals
Large intrinsic anomalous Hall effect (AHE) due to the Berry curvature in magnetic topological semimetals is attracting enormous interest due to its fundamental importance and technological relevance. Mechanisms resulting in large intrinsic AHE include diverging Berry curvature in Weyl semimetals, anticrossing nodal ri...
2301.01074v1
2020-10-09
Structural and magnetic properties of epitaxial films of CoIrMnAl equiatomic quaternary Heusler alloy designed from first-principles calculation
MgO-barrier magnetic tunnel junctions with half-metallic Heusler alloy electrodes attracted much attentions for spintronics applications. However, a couples of issues related to materials still remain to be resolved for practical uses. Recently, quarterly equiatomic Heusler alloys attracted attentions as advanced Heusl...
2010.04369v1
2021-02-22
High T$_C$ ferromagnetic inverse Heusler alloys: A comparative study of Fe$_2$RhSi and Fe$_2$RhGe
We report the results of experimental investigations on structural, magnetic, resistivity, caloric properties of Fe$_2$RhZ (Z=Si,Ge) along with \textit{ab-initio} band structure calculations using first principle simulations. Both these alloys are found to crystallize in inverse Heusler structure but with disorder in t...
2102.10967v1
2004-07-21
Orbital magnetism in the half-metallic Heusler alloys
Using the fully-relativistic screened Korringa-Kohn-Rostoker method I study the orbital magnetism in the half-metallic Heusler alloys. Orbital moments are almost completely quenched and they are negligible with respect to the spin moments. The change in the atomic-resolved orbital moments can be easily explained in ter...
0407560v1
1996-07-01
On the Uniqueness of the Papapetrou--Majumdar Metric
We establish the equality of the ADM mass and the total electric charge for asymptotically flat, static electrovac black hole spacetimes with completely degenerate, not necessarily connected horizon.
9607001v1
2013-01-03
Enhanced thermoelectric performance in TiNiSn-based half-Heuslers
Thermoelectric figures of merit, ZT > 0.5, have been obtained in arc-melted TiNiSn-based ingots. This promising conversion efficiency is due to a low lattice thermal conductivity, which is attributed to excess nickel in the half-Heusler structure.
1301.0419v1
2014-09-23
The shifts X-Ray Mn Kα and 2p spectra of Mn-Heusler alloys
X-ray emission K{\alpha}1,2 spectra of Mn in Heusler alloys Co2MnMe (Me = Al, Ga, Sb), Ni2MnIn, Cu2MnAl were studied. Shifts of Mn K{\alpha}1,2 lines relatively pure Mn in high-energy region and low-energy shifts of binding energy Mn 2p XPS is detected. X-ray emission and XPS shifts are in qualitative agreement.
1409.6375v1
2014-10-08
Direct Measurement of Magnetocaloric Effect in Metamagnetic Ni43Mn37.9In12.1Co7 Heusler Alloy
The magnetocaloric effect in the metamagnetic Ni43Mn37.9In12.1Co7 Heusler alloy is directly studied experimentally under the adiabatic and quasi-isothermal conditions in a magnetic field with induction of up to 14 T.
1410.2139v1
2023-02-13
Structural, magnetic and elastic properties on stoichometric $Ni-Mn-Cu$ Heusler alloys
Heusler alloys with $Ni-Mn-Cu$ (all d-transition metal) composition have been studied; equilibrium structures for different magnetic configurations are found. Elastic constants and tetragonal distortion are analyzed. Distortion effect on densities of electronic state peaks are characterized. For this ternary family of ...
2302.06472v2
2009-08-09
Synthetic antiferromagnet with Heusler alloy Co2FeAl ferromagnetic layers
Heusler alloy Co2FeAl was employed as ferromagnetic layers in Co2FeAl/Ru/Co2FeAl synthetic antiferromagnet structures. The experimental results show that the structure with a Ru thickness of 0.45 nm takes on strongly antiferromagnetic coupling, which maintains up to 150 oC annealing for 1 hour. The structure has a very...
0908.1215v1
2010-02-08
Quantitative analysis of atomic disorders in full-Heusler Co2FeSi alloy thin films using x-ray diffraction with Co-Ka and Cu-Ka sources
The authors developed a new analysis technique for atomic disorder structures in full-Heusler alloys using x-ray diffraction (XRD) with Co-Ka and Cu-Ka sources. The developed technique can quantitatively evaluate all the atomic disorders for the exchanges between X, Y, and Z atoms in full-Heusler X2YZ alloys. In partic...
1002.1564v1
2013-11-08
Electronic, magnetic and transport properties of full and half-metallic thin film Heusler alloys
The electronic and magnetic bulk properties of half-metallic Heusler alloys such as Co$_{2}$FeSi, Co$_{2}$FeAl, Co$_{2}$MnSi and Co$_{2}$MnAl are investigated by means of {\em ab initio} calculations in combination with Monte Carlo simulations. The electronic structure is analyzed using the plane wave code Quantum Espr...
1311.1950v1
2014-04-17
Large Noncollinearity and Spin Reorientation in the Novel Mn2RhSn Heusler Magnet
Noncollinear magnets provide essential ingredients for the next generation memory technology. It is a new prospect for the Heusler materials, already well known due to the diverse range of other fundamental characteristics. Here, we present a combined experimental and theoretical study of novel noncollinear tetragonal ...
1404.4581v2
2015-03-10
Vanadium sacrificial layers as a novel approach for the fabrication of freestanding Heusler Shape Memory Alloys
In this study we report a method for the preparation of freestanding magnetocaloric thin films. Non-stoichiometric Heusler alloys Ni-Mn-Sn, Ni-Co-Mn-Sn and Ni-Co-Mn-Al are prepared via sputter deposition. A sacrificial vanadium layer is added between the substrate and the Heusler film. By means of selective wet-chemica...
1503.02987v1
2015-05-28
Uncovering High Thermoelectric Figure of Merit in (Hf,Zr)NiSn Half-Heusler Alloys
Half-Heusler alloys (MgAgSb structure) are promising thermoelectric materials. RNiSn half-Heusler phases (R=Hf, Zr, Ti) are the most studied in view of their thermal stability. The highest dimensionless figure of merit (ZT) obtained is ~1 in the temperature range ~450-900oC, primarily achieved in nanostructured alloys....
1505.07773v2
2017-11-01
Tunable magnetization relaxation of Fe_{2}Cr_{1-x}Co_{x}Si half-metallic Heusler alloys by band structure engineering
We report a systematic investigation on the magnetization relaxation properties of iron-based half-metallic Heusler alloy Fe$_{2}$Cr$_{1-x}$Co_${x}$Si (FCCS) thin films using broadband angular-resolved ferromagnetic resonance. Band structure engineering through Co doping (x) demonstrated by first-principles calculation...
1711.00406v1
2018-06-13
Minimizing hysteresis in martensite phase transforming magnetocaloric Heusler alloys
The large magnetocaloric effect in Heusler alloys showing martensite phase transformation puts them forward as efficient materials for magnetic refrigeration. However, irreversibility of the magnetocaloric cooling cycle is a major challenge for real applications. This irreversibility is directly linked to the thermal h...
1806.05075v1
2018-09-04
Increasing the performance of the superconducting spin valve using a Heusler alloy
We have studied superconducting properties of the spin-valve thin layer heterostructures CoO$_x$/F1/Cu/F2/Cu/Pb where the ferromagnetic F1 layer was standardly made of Permalloy whereas for the F2 layer we have taken a specially prepared film of the Heusler alloy Co$_2$Cr$_{1-x}$Fe$_x$Al with a small degree of spin pol...
1809.00876v1
2018-12-14
Formation of two-dimensional electron and hole gases at the interface of half-Heusler semiconductors
Heuslers are a prominent family of multi-functional materials that includes semiconductors, half metals, topological semimetals, and magnetic superconductors. Owing to their same crystalline structure, yet quite different electronic properties and flexibility in chemical composition, Heusler-based heterostructures can ...
1812.05991v1
2020-04-02
Reversible adiabatic temperature change in the shape memory Heusler alloy Ni2.2Mn0.8Ga: An effect of structural compatibility
The large magnetocaloric effect (MCE) observed in Ni-Mn based shape-memory Heusler alloys put them forward to use in magnetic refrigeration technology. It is associated with a first-order magnetostructural (martensitic) phase transition. We conducted a comprehensive study of the MCE for the off-stoichiometric Heusler a...
2004.00949v1
2020-05-07
Structural and magnetic behavior of Cr$_2$Co$_{(1-x)}$Cr$_x$Al inverse Heusler alloys
We report the structural and magnetic behavior of single phase inverse Heusler alloys Cr$_2$Co$_{(1-x)}$Cr$_x$Al ($x = $ 0, 0.2, 0.4) using x-ray diffraction (XRD), Raman spectroscopy, isothermal magnetization, and magnetic susceptibility measurements. Interestingly, the Rietveld refinement of XRD data with the space g...
2005.03528v1
2016-12-19
How to enable bulk-like martensitic transformation in epitaxial films
The present study is dedicated to the influence of different substrate and buffer layer materials on the martensitic transformation in sputter deposited epitaxial shape memory Heusler alloys. For this, the magnetocaloric Heusler alloy Ni-Co-Mn-Al \cite{Teichert2015b} is grown on MgO(001), MgAl$_{2}$O$_{4}$(001), and Mg...
1612.06077v1
2017-06-14
Temperature-dependent Gilbert damping of Co2FeAl thin films with different degree of atomic order
Half-metallicity and low magnetic damping are perpetually sought for in spintronics materials and full Heusler alloys in this respect provide outstanding properties. However, it is challenging to obtain the well-ordered half-metallic phase in as-deposited full Heusler alloys thin films and theory has struggled to estab...
1706.04670v2
2021-08-04
Theory of Huge Thermoelectric Effect Based on Magnon Drag Mechanism: Application to Thin-Film Heusler Alloy
To understand the unexpectedly high thermoelectric performance observed in the thin-film Heusler alloy Fe$_2$V$_{0.8}$W$_{0.2}$Al, we study the magnon drag effect, generated by the tungsten based impurity band, as a possible source of this enhancement, in analogy to the phonon drag observed in FeSb$_2$. Assuming that t...
2108.01880v1
2022-04-13
Influence of Co and Mn on Electronic and Magnetic properties of Ni2MnGa Heusler alloy
The ferromagnetic Heusler alloy $Ni_2MnGa$ had been of major interest in the past few years because of its magnetic properties which can be easily tuned. The $Ni_2MnGa$ Heusler alloys are intermetallic alloy with $L2_1$ structure. Here we report a detailed investigation of the effect of doping of Co and Mn in Ni2MnGa. ...
2204.06140v4
2023-06-25
First-principles study of disordered half-Heusler alloys \textit{X}Fe$_{0.5}$Ni$_{0.5}$Sn (\textit{X} = Nb, Ta) as thermoelectric prospects
High lattice thermal conductivity in half-Heusler alloys has been the major bottleneck in thermoelectric applications. Disordered half-Heusler alloys could be a plausible alternative to this predicament. In this paper, utilizing first-principles simulations, we have demonstrated the low lattice thermal conductivity in ...
2306.14234v1
2021-11-09
Effect of substitutional doping and disorder on the phase stability, magnetism, and half-metallicity of Heusler alloys
Spintronics is the fast growing field that will play a key role in optimizing power consumption, memory, and processing capabilities of nanoelectronic devices. Heusler alloys are potential candidates for application in spintronics due to their room temperature (RT) half-metallicity, high Curie temperature, low lattice ...
2111.05179v1
2010-10-14
Pressure dependence of Curie temperature and resistivity in complex Heusler alloys
Using first-principles electronic structure calculations, we have studied the dependence of the Curie temperature on external hydrostatic pressure for random Ni2MnSn Heusler alloys doped with Cu and Pd atoms, over the entire range of dopant concentrations. The Curie temperatures are calculated by applying random-phase ...
1010.3025v2
2017-06-06
Designing magnetism in Fe-based Heusler alloys: a machine learning approach
Combining material informatics and high-throughput electronic structure calculations offers the possibility of a rapid characterization of complex magnetic materials. Here we demonstrate that datasets of electronic properties calculated at the ab initio level can be effectively used to identify and understand physical ...
1706.01840v1
2019-05-20
Band alignment and scattering considerations for enhancing the thermoelectric power factor of complex materials: The case of Co-based half-Heuslers
Half-Heuslers, an emerging thermoelectric material group, has complex bandstructures with multiple bands that can be aligned through band engineering approaches, giving us an opportunity to improve their power factor. In this work, going beyond the constant relaxation time approximation, we perform an investigation of ...
1905.07951v1