arXiv subjects

Orest Pavlosiuk

Publications and source records attributed to Orest Pavlosiuk.

At least 19 recordsLinked to original sources

arXiv2026

Thermodynamic and electrical transport properties of the half-Heusler plumbide TbAuPb

Structural, thermodynamic and electrical transport properties of TbAuPb were investigated on single crystals. The compound was found to crystallize with the cubic MgAgAs-type structure characteristic of half-Heusler materials. It orders antiferromagnetically at TN = 5 K and undergoes a transition into a different antiferromagnetic phase emerging in high magnetic fields. Electrical transport in TbAuPb exhibits a multiband character, with a predominance of hole-like carriers. Angular magnetoresistance evolves systematically with applied magnetic field and changes its symmetry near the spin-reorientation transition, highlighting strong coupling between the charge transport and the magnetic order. The results of first-principles calculations indicate that TbAuPb is a band inverted semimetal in the non-magnetic state, which becomes topologically trivial in the field-induced ferromagnetic state.

cond-mat.str-el↗

arXiv2026

Magnetotransport and electronic band structure of EuNi$_2$As$_2$ antiferromagnet

We investigated the magnetotransport properties of single-crystals of tetragonal van der Waals compound EuNi$_2$As$_2$, that orders antiferromagnetically below 14.6 K in an incommensurate helical structure. Metamagnetic transitions are revealed by the magnetization measured in the magnetic field applied transverse to the axis of the helix, and are clearly reflected in the magnetoresistance. Overall, the magnetoresistance is small, but shows complex changes with the temperature, the strength, and the angle of the applied magnetic field. In magnetically ordered state, magnetoresistance shows prominent anomalies related to the metamagnetic transitions. For temperatures above the Néel point the negative magnetoresistance can be modeled very well with de Gennes-Friedel mechanism of the spin-disorder-scattering reduction. Hall resistivity data indicate hole-dominated multi-band conductivity in antiferromagnetic state and single-band one above the Néel temperature, with carrier concentrations of the order of 10$^{22}$cm$^{-3}$. This metallic character of the compound seems to obscure the plausible topological contribution to the Hall resistivity. Our \textit{ab-initio} calculations of electronic band structure showed that the electronic structure changes very strongly upon magnetic ordering, but the density of states at the Fermi level differs by a factor smaller than two, in agreement with experimental Hall resistivity data. Meaningful changes in the density of states, magnetic moments, and screening length of Eu-4$f$ orbitals are discussed in terms of the effects of Hubbard corrections.

cond-mat.mtrl-sci↗

arXiv2026

Transverse and Longitudinal Magnetothermopower Promoted by Ambipolar Effect in Half-Heusler Topological Materials

Topologically trivial and non-trivial semimetals with a high degree of carrier compensation are well known for demonstrating large transverse magnetothermopower ($S_{yx}$). However, in such systems, the longitudinal magnetothermopower ($S_{xx}$) is typically suppressed due to nearly perfect electron-hole compensation. Here, we show that the half-Heusler topological semimetal DyPtBi exhibits simultaneously large $S_{xx}$ and $S_{yx}$ magnetothermopowers, defying this conventional trade-off. In $B=14$\,T, thermopower of DyPtBi reaches peak values of $S_{xx}=131\,μ\rm{V/K}$ at $T=149$\,K and $S_{yx}=-297\,μ\rm{V/K}$ at $T=200$\,K, and transverse component remains significantly large even at $290$\,K ($S_{yx}=-213\,μ\rm{V/K}$). Remarkably, at $T=290$\,K and in relatively weak magnetic field of $1$\,T, both relevant for practical applications, DyPtBi shows $S_{yx}=-18\,μ\rm{V/K}$, which is one of the largest values reported under such conditions. The large transverse thermopower originates from an ambipolar effect associated with thermal excitation occurring in zero-gap semiconductors. Due to the imperfect electron-hole compensation, an intrinsic asymmetry between hole- and electron-type carriers enables pronounced values of both $S_{xx}$ and $S_{yx}$, resulting in high effective thermopower ($S_{xx}+|S_{yx}|=379\,μ\rm{V/K}$) in DyPtBi at 200\,K. A comparative analysis with DyPdBi, another half-Heusler material that demonstrates large $S_{xx}=123\,μ\rm{V/K}$ but small $S_{yx}=-16\,μ\rm{V/K}$ (both values obtained at $T=293$\,K and $B=14$\,T), highlights the critical role of band structure and compensation tuning. These findings underscore the potential of chemical doping and band engineering in rare-earth-based half-Heusler materials for optimizing both transverse and longitudinal thermoelectric properties.

cond-mat.mtrl-sci↗

arXiv2026

Tuning of anomalous magnetotransport properties in half-Heusler topological semimetal GdPtBi

Half-Heusler compounds from the $RE$PtBi family exemplify Weyl semimetals in which external magnetic field induce Weyl nodes. These materials exceptionally host topologically non-trivial states near the Fermi level and their manifestation can be clearly seen in the magnetotransport properties. In this study, we tune the Fermi level of the archetypal half-Heusler Weyl semimetal GdPtBi through high-energy electron irradiation, moving it away from the Weyl nodes to investigate the resilience of the contribution of topologically non-trivial states to magnetotransport properties. Remarkably, we observe that the negative longitudinal magnetoresistance, which is a definitive indicator of the chiral magnetic anomaly occurring in topological semimetals, persists even when the Fermi level is shifted by 100\,meV from its original position in the pristine sample. Additionally, the anomalous Hall effect shows complex variations as the Fermi level is altered, attributed to the energy-dependent nature of the Berry curvature, which arises from avoided band crossing. Our findings show the robust influence of Weyl nodes on the magneto-transport properties of GdPtBi, irrespective of the Fermi level position, a behaviour likely applicable to many half-Heusler Weyl semimetals.

cond-mat.mtrl-sci↗

arXiv2026

Anomalous magnetotransport in the single-crystalline half-Heusler antiferromagnet ErPdSb

We report the thermodynamic and magnetotransport properties of the half-Heusler antimonide ErPdSb, studied on single-crystalline samples in wide ranges of temperature and magnetic fields. The compound was found to order antiferromagnetically at 1.2 K. In the paramagnetic state, it shows semimetallic behavior with a broad hump in the temperature-dependent electrical resistivity around 70 K. The results of ab initio calculations of the electronic structure of ErPdSb indicated a bulk insulating nature. In small magnetic fields the magnetoresistance is driven by a weak antilocalization effect, while in strong fields it is negative and describable by the deGennes-Friedel formalism. The Hall effect data indicated that holes are the dominant charge carriers. At 2 K, the Hall conductivity exhibits a sizable anomalous contribution, which is obscured by multiband effects at higher temperatures. The angular magnetoresistance shows unusual features as functions of magnetic field and temperature, pointing to a possible field-induced reconstruction of the Fermi surface.

cond-mat.str-el↗

arXiv2026

Magnetic and electrical transport properties of the single-crystalline half-Heusler antiferromagnet DyNiSb

High-quality single crystals of the half-Heusler compound DyNiSb were investigated for their low temperature thermodynamic and magnetotransport properties. Magnetic susceptibility, heat capacity, and electrical resistivity measurements revealed two distinct magnetic phase transitions at TN1 = 7.3 K and TN2 = 3.4 K, contrasting with previous reports on polycrystalline samples, which identified only a single transition near TN2 . Moreover, the studied samples were found to exhibit Metal like conductivity, at odds with a semiconducting behavior reported for the polycrystals. Magnetoresistance measurements performed in both transverse and longitudinal configurations revealed in small magnetic fields a weak antilocalization effect that diminishes with increasing temperature, giving way to a positive, monotonic magnetoresistance at high temperatures. Angular-dependent resistivity studies showed a crossover from fourfold to twofold symmetry with increasing magnetic-field strength, suggesting a field-induced reconstruction of the Fermi surface. Our findings highlight a complex magnetic and electrical transport behavior in DyNiSb, highly sensitive to structural disorder and easily tunable by external magnetic field.

cond-mat.str-el↗

arXiv2026

Origin of the large topological Hall effect in the EuCd$_2$Sb$_2$ antiferromagnet

We study the origin of large topological Hall effect in the single-crystalline EuCd$_2$Sb$_2$, which orders antiferromagnetically at the Néel temperature $T_{\rm N}=7.4$ K. Measurements of magnetoresistance and Hall resistivity disclose anomalies that evolve with temperature and magnetic field, closely tracking the magnetization process. Analysis of these data identifies three possible mechanisms responsible for the enhanced Berry curvature driving the observed topological Hall effect. Below and above $T_{\rm N}$, Weyl states are the main sources of large momentum-space Berry curvature, though their formation mechanisms differ in these two temperature ranges. Below $T_{\rm N}$, breaking of $C_{3}$ symmetry generates Dirac points that split into Weyl nodes in applied magnetic field, whereas above $T_{\rm N}$, strong spin fluctuations can induce Weyl states. The third contribution, which occurs below $T_{\rm N}$, arises from scalar spin chirality developing within antiferromagnetic domain walls, which generates a real-space Berry curvature.

cond-mat.mtrl-sci↗

arXiv2025

Nature of field-induced transitions and hysteretic magnetoresistance in non-collinear antiferromagnet EuIn2As2

We examine the magnetic and electrical transport properties of the hexagonal EuIn2As2 compound, combining experimental and theoretical results. This compound is predicted to be an axion-insulator from an electronic point of view and an altermagnet while in the collinear magnetic phase. However, experiments indicate that the Fermi level lies within the valence band rather than in the topological gap, potentially leading to the dominance of magnetic properties. Our detailed studies on magnetization and electrical transport support the presence of a broken-helix antiferromagnetic state, which was previously identified by X-ray and neutron diffraction experiments. Notably, we observed within that state a field-induced metamagnetic transition marked by a large hysteresis in magnetoresistance, which turns into a sharp upturn for the magnetic field tilted by 15 degree from the c-axis of the crystal. Combined with theoretical calculations, it is explained that the application of a magnetic field changes the low-resistivity antiferromagnetic domain walls to the high-resistivity domain walls due to the reduction in the Fermi surface sheets interaction area in the domain walls, originating from p-orbitals of As. EuIn2As2, therefore, presents a new case study that broadens the understanding of complex magnetic structures and their influence on electrical transport.

cond-mat.mtrl-sci↗

arXiv2025

Giant magneto-cubic in-plane Hall effect in a nonmagnetic material

In-plane Hall effect (IPHE) triggered by an external magnetic field applied in the transport plane has attracted significant experimental attentions in recent few years 1-6. However, most experiments focus on magnetic materials, where the existence of magnetic ordering may complicate understanding the physics behind, and the relatively small signal magnitudes limit the application of the effect. Here, we report a giant IPHE in a nonmagnetic half-Heusler compound LuAuSn, with a magnitude exceeding all the previously reported values. A -period of IPHE and the consistent cubic dependence on the magnetic field are observed, realizing the long-sought theoretical prediction of magneto-cubic IPHE under threefold rotational symmetry7-9 in an unexpected material. The scaling law analysis and first-principles calculations indicate that extrinsic side jump and skew scattering processes from both impurity and phonon scatterings dominate the observed effect. These findings unravel a new type of magneto-nonlinear IPHE, and its large magnitude and wide-temperature operation may open the door to practical applications of IPHE.

cond-mat.mtrl-sci↗

arXiv2025

Insulating Half-Heusler TmPdSb with Unusual Band Order and Metallic Surface States

We present theoretical and experimental results exploring a half-Heusler compound TmPdSb with unusual band order and metallic surface states. Typically, the half-Heusler systems exhibit topological features in a semimetallic state, and trivial ones in an insulating state. Topological properties of the most of half-Heusler systems are related to the band inversion around the Fermi level, similar to this observed in CdTe/HgTe systems. In the case of TmPdSb we observed the gapped electronic band structure with ``band inversion'' in the conductance band, while the slab-like system realized metallic surface states. The bulk insulating nature of the compound was corroborated by means of electrical transport measurements. The experimental data revealed several features due to the presence of metallic surface states, such as linear magnetoresistance and weak-antilocalization effect, characterized by enhanced coherence length and a very large number of surface conductive channels. Our findings reveal new features of the rare-earth half-Heusler.

cond-mat.mtrl-sci↗

arXiv2024

Evidence of variable range hopping in the Zintl phase EuIn2P2

We report a comprehensive characterization of the magnetic, electrical transport, spectral, and thermal properties of single-crystalline Zintl-type material EuIn2P2. The compound crystallizes with a hexagonal unit cell (space group P63/mmc) and orders magnetically at TC=24K with the Eu magnetic moments aligned ferromagnetically within the ab plane but tilted alternately along the c-axis direction. The effective and saturation magnetic moments agree with the theoretical values expected for the Eu2+ ion. For a range of several tens of kelvins above 40K, the electrical transport of EuIn2P2 is dominated by short-range magnetic interactions. The temperature dependence of the electrical resistivity has been modelled in terms of variable-range hopping. Another indication of the latter scenario seems to be the observation for EuIn2P2 of a quadratic dependence of the negative magnetoresistance on the magnetic field strength and the scaled magnetization. The temperature dependence of Raman band position and FWHM, as well as phonon lifetime, confirms the presence of the distinctive regions observed in transport and magnetic studies.

cond-mat.mtrl-sci↗

arXiv2024

Large unconventional anomalous Hall effect arising from spin chirality within domain walls of an antiferromagnet EuZn$_2$Sb$_2$

Unconventional anomalous Hall effect was observed in antiferromagnetic state of EuZn$_2$Sb$_2$. Scaling of unconventional Hall conductivity with the longitudinal conductivity, and the magnitude of Hall angle indicate spin chirality despite collinear magnetic structure. Anomalies in magnetoresistance culminate in the same fields, in which the unconventional anomalous Hall resistance has maxima. Monotonous decrease of their magnitude with increasing temperature belittles here the role of spin-fluctuations, important in isostructural compounds. These observations point to a prominent role of scalar spin chirality within domain walls, when magnetic field tilts the Eu moments. Simple calculation of such spin chirality shows it strongest in fields characteristic for anomalous magnetotransport.

cond-mat.mtrl-sci↗

arXiv2024

Temperature-dependent Fermi surface probed by Shubnikov-de Haas oscillations in topological semimetal candidates DyBi and HoBi

Rare earth-based monopnictides are among the most intensively studied groups of materials in which extremely large magnetoresistance has been observed. This study explores magnetotransport properties of two representatives of this group, DyBi and HoBi. The extreme magnetoresistance is discovered in DyBi and confirmed in HoBi. At $T=2$ K and in $B=14$ T for both compounds, magnetoresistance reaches the order of magnitude of $10^4\%$. For both materials, standard Kohler's rule is obeyed only in the temperature range from 50 K to 300 K. At lower temperatures, extended Kohler's rule has to be invoked because carrier concentrations and mobilities strongly change with temperature and magnetic field. This is further proven by the observation of a quite rare temperature-dependence of oscillation frequencies in Shubnikov-de Haas effect. Rate of this dependence clearly changes at Néel temperature, reminiscent of a novel magnetic band splitting. Multi-frequency character of the observed Shubnikov-de Haas oscillations points to the coexistence of electron- and hole-type Fermi pockets in both studied materials. Overall, our results highlight correlation of temperature dependence of the Fermi surface with the magnetotransport properties of DyBi and HoBi.

cond-mat.mtrl-sci↗

arXiv2022

Investigation of metamagnetism and crystal-field splitting in pseudo-hexagonal CeRh$_3$Si$_2$

CeRh$_3$Si$_2$ has been reported to exhibit metamagnetic transitions below 5~K, a giant crystal field splitting, and anisotropic magnetic properties from single crystal magnetization and heat capacity measurements. Here we report results of neutron and x-ray scattering studies of the magnetic structure and crystal-field excitations to further understand the magnetism of this compound. Inelastic neutron scattering (INS) and resonant inelastic x-ray scattering (RIXS) reveal a $J_z$\,=\,1/2 groundstate for Ce when considering the crystallographic $a$ direction as quantization axis, thus explaining the anisotropy of the static susceptibility. Furthermore, we find a total splitting of 78\,meV for the $J$\,=\,5/2 multiplet. The neutron diffraction study in zero field reveals that on cooling from the paramagnetic state, the system first orders at $T_{\text{N}_1}=4.7$\,K in a longitudinal spin density wave with ordered Ce moments along the $b$-axis (i.e. the [0 1 0] crystal direction) and an incommensurate propagation vector $\textbf{k}=(0,0.43,0$). Below the lower-temperature transition $T_{\text{N}_2}=4.48$\,K, the propagation vector locks to the commensurate value $\textbf{k}=(0,0.5,0)$, with a so-called lock-in transition. Our neutron diffraction study in applied magnetic field $H\parallel b$-axis shows a change in the commensurate propagation vector and development of a ferromagnetic component at $H=3$\,kOe, followed by a series of transitions before the fully field-induced ferromagnetic phase is reached at $H = 7$\,kOe. This explains the nature of the steps previously reported in field-dependent magnetization measurements. A very similar behaviour is also observed for the $H\parallel$ [0 1 1] crystal direction.

cond-mat.str-el↗

arXiv2022

Giant magnetoresistance, Fermi surface topology, Shoenberg effect and vanishing quantum oscillations in type-II Dirac semimetal candidates MoSi$_2$ and WSi$_2$

We performed comprehensive theoretical and experimental studies of the electronic structure and the Fermi surface topology of two novel quantum materials, MoSi$_2$ and WSi$_2$. The theoretical predictions of the electronic structure in the vicinity of the Fermi level was verified experimentally by thorough analysis of the observed quantum oscillations in both electrical resistivity and magnetostriction. We established that the Fermi surface sheets in MoSi$_2$ and WSi$_2$ consist of 3D dumbbell-shaped hole-like pockets and rosette-shaped electron-like pockets, with nearly equal volumes. Based on this finding, both materials were characterized as almost perfectly compensated semimetals. In conjunction, the magnetoresistance attains giant values of $10^4$ and $10^5\,\%$ for WSi$_2$ and MoSi$_2$, respectively. In turn, the anisotropic magnetoresistance achieves $-95$ and $-98\,\%$ at $T=2\,$K and in $B=14\,$T for WSi$_2$ and MoSi$_2$, respectively. Furthermore, for both compounds we observed the Shoenberg effect in their Shubnikov-de Haas oscillations that persisted at as high temperature as $T=25\,$K in MoSi$_2$ and $T=12\,$K in WSi$_2$. In addition, we found for MoSi$_2$ a rarely observed spin-zero phenomenon. Remarkably, the electronic structure calculations revealed type-II Dirac cones located near 480 meV and 710 meV above the Fermi level in MoSi$_2$ and WSi$_2$, respectively.

cond-mat.mtrl-sci↗

arXiv2021

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 distinct property of topological semimetals. Electronic structure calculations show that structural defects, such as antisites and vacancies, bring substantial density of states at the Fermi level of ScPtBi, indicating that it is a semimetal, not a zero-gap semiconductor, as predicted earlier. This is in accord with electrical resistivity in ScPtBi, showing no characteristics of semiconductor. Moreover, below 0.7K we observed an onset of a superconducting transition, with the resistivity disappearing completely below 0.23 K.

cond-mat.mtrl-sci↗

arXiv2020

Anomalous Hall effect and negative longitudinal magnetoresistance in half-Heusler topological semimetal candidates TbPtBi and HoPtBi

Half-Heusler compounds have attracted significant attention because of their topologically non-trivial electronic structure, which leads to unusual electron transport properties. We thoroughly investigated the magnetotransport properties of high-quality single crystals of two half-Heusler phases, TbPtBi and HoPtBi, in pursuit of the characteristic features of topologically non-trivial electronic states. Both studied compounds are characterized by the giant values of transverse magnetoresistance with no sign of saturation in magnetic field up to 14 T. HoPtBi demonstrates the Shubnikov-de Haas effect with two principal frequencies, indicating a complex Fermi surface; the extracted values of carrier effective masses are rather small, $0.18\,m_e$ and $0.27\,m_e$. The investigated compounds exhibit negative longitudinal magnetoresistance and anomalous Hall effect, which likely arise from a nonzero Berry curvature. Both compounds show strongly anisotropic magnetoresistance, that in HoPtBi exhibits a butterfly-like behavior.

cond-mat.mtrl-sci↗

arXiv2020

Observation of gapped state in rare-earth monopnictide HoSb

The rare-earth monopnictide family is attracting an intense current interest driven by its unusual extreme magnetoresistance (XMR) property and the potential presence of topologically non-trivial surface states. The experimental observation of non-trivial surface states in this family of materials are not ubiquitous. Here, using high-resolution angle-resolved photoemission spectroscopy (ARPES), magnetotransport, and parallel first-principles modeling, we examine the nature of electronic states in HoSb. Although we find the presence of bulk band gaps at the G and X-symmetry points of the Brillouin zone (BZ), we do not find these gaps to exhibit band inversion so that HoSb does not host a Dirac semimetal state. Our magnetotransport measurements indicate that HoSb can be characterized as a correlated nearly-complete electron-hole-compensated semimetal. Our analysis reveals that the nearly perfect electron-hole compensation could drive the appearance of non-saturating XMR effect in HoSb.

cond-mat.mes-hall↗