arXiv subjects

Dariusz Kaczorowski

Publications and source records attributed to Dariusz Kaczorowski.

At least 19 recordsLinked to original sources

arXiv2026

Staged emergence of anomalous Hall transport in a correlated uranium Weyl semimetal

Understanding how electronic correlations reshape topological states remains a central challenge in quantum materials. Here we investigate the uranium ferromagnet UPS using magnetotransport, angle-resolved photoemission spectroscopy, thermodynamic measurements, and first principles calculations. Resonant photoemission reveals narrow U-$5f$ spectral weight at the Fermi level coexisting with broad incoherent states, consistent with the itinerant/localized duality characteristic of uranium $5f$ electrons. The anomalous Hall conductivity reaches approximately $4.5\times10^{2}\,Ω^{-1}\mathrm{cm}^{-1}$, yet does not simply follow the ordered magnetic moment. Temperature dependent photoemission reveals relatively little change across $T_C=118$~K, followed by a pronounced redistribution of low-energy $5f$ spectral weight below approximately 90~K. First-principles calculations identify a symmetry protected Weyl crossing with pronounced Berry curvature and yield an intrinsic anomalous Hall conductivity of approximately $9.6\times10^{2}\,Ω^{-1}\mathrm{cm}^{-1}$. These results demonstrate that magnetic order, correlated electronic reconstruction, and anomalous Hall transport develop over distinct but overlapping temperature ranges, revealing how strong correlations reshape topological transport in a uranium Weyl semimetal.

cond-mat.str-el↗

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

Imaging the Magnetically Driven Reconstruction of the Electronic States in the Antiferromagnetic Topological Insulator EuSn$_2$As$_2$

The realization of the axion insulator phase in magnetic topological insulators is often hindered by crystalline symmetries that protect gapless surface states, even when time-reversal symmetry is broken. Here, we use variable-temperature scanning tunneling microscopy (STM) and spectroscopy (STS), complemented with density functional theory (DFT), to investigate the local electronic structure of the antiferromagnetic (AFM) topological insulator EuSn$_2$As$_2$ across its Néel transition at $T_N = 24$ K. On the (001) surface, we observe a substantial density of intrinsic Sn vacancies that introduce nanoscale electronic inhomogeneity and p-type doping. Upon cooling below $T_N$, we resolve the emergence of two distinct magnetically driven gaps: a $\sim$100 meV gap near the Fermi level and a $\sim$50 meV gap at the ARPES-resolved Dirac point. We attribute the former gap to AFM Brillouin-zone folding and hybridization. The characteristics of the 50 meV gap point toward the lifting of mirror-symmetry protection by Sn vacancies and the consequent mass gapping of the Dirac point, although contributions from AFM-induced folding hybridization cannot be entirely ruled out. Our findings provide real-space evidence for strong coupling between localized moments and itinerant topological states, highlighting exfoliable EuSn$_2$As$_2$ as a potential candidate for realizing axion-insulator-based devices.

cond-mat.str-el↗

arXiv2026

Observation of the Optical Phonons in α-MnTe films

The altermagnetic materials have emerged as model systems for studying spin split electronic structures, yet controlled epitaxial growth on technologically relevant substrates remains challenging. Among the known candidates, MnTe stands out as a prominent altermagnetic material owing to its layered structure and high Neel temperature. Here, we report the molecular beam epitaxy (MBE) growth of high quality alpha MnTe thin films on GaAs(111)B substrates and provide a comprehensive analysis of the growth evolution and structural properties. Raman spectroscopy reveals multiple vibrational features of alpha MnTe including modes near 121, and 140 1/cm. Combined with first principles phonon calculations, these features are identified as the Raman-active phonons of the hexagonal NiAs type lattice. Our results show that the high crystalline quality of MBE grown alpha MnTe enables the complete experimental resolution of all symmetry allowed Raman active phonon modes, highlighting epitaxial alpha MnTe as a robust thin film platform for investigating altermagnetism and its lattice coupled excitations.

cond-mat.mes-hall↗

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

Topological character of the antiferromagnetic EuMg$_{2}$Bi$_{2}$

Antiferromagnetic EuM$_{2}$Pn$_{2}$ compounds, where M is a metal element and Pn is a pnictogen element, have been recognized as candidates for realizing a topologically nontrivial electronic structure. In this paper, we focus on EuMg$_2$Bi$_2$, whose topological nature still remains unclear. We present a comprehensive study based on several experimental and theoretical techniques. Magnetic susceptibility, electrical resistivity, and specific heat capacity measurements confirm the existence of an antiferromagnetic ordering. The electronic band structure was investigated by high-resolution angle-resolved photoemission spectroscopy (ARPES), supported by ab initio calculations. ARPES measurement reveals that the electronic structure of this system is dominated by linearly dispersive hole-like bands near the Fermi level. Theoretical analyses of the electronic band structure indicates that EuMg$_2$Bi$_2$ is a strong topological insulator, which should be reflected in the presence of a metallic surface state. We also theoretically examine the magnetic-field-induced anomalous Hall conductivity, confirming previously reported observations.

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

Topologically trivial semiconducting behavior and polaronic effects in antiferromagnetic EuZn$_2$As$_2$ and EuCd$_2$Sb$_2$

The Eu-based EuA$_2$X$_2$ (A = Zn, Cd, In, Sn; X = P, As, Sb) family of compounds has recently attracted significant attention as a promising platform for exploring magnetic topological materials, with several members either predicted or reported to exhibit nontrivial topological properties. We investigate the previously reported topological semimetals, EuZn$_2$As$_2$ and EuCd$_2$Sb$_2$, using scanning tunneling microscopy and spectroscopy, complemented by various first-principles computational approaches. Through examination of the cleaved surfaces, step-edges, and defect states, we determine the trivial semiconducting behavior in both material systems, with no evidence of topological surface or edge states. These experimental results are consistent with our theoretical analysis revealing the absence of topological band inversion in either system. Our experimental observations also reveal numerous intrinsic defects that trap charge carriers. These defects may facilitate the formation of magnetic polarons, providing a natural explanation for the colossal negative magnetoresistance observed in many of the EuA$_2$X$_2$ material systems.

cond-mat.str-el↗

arXiv2025

Electronic Structure of a Nodal Line Semimetal Candidate TbSbTe

The LnSbTe (Ln = Lanthanides) family, like isostructural ZrSiS type compounds, has emerged as a fertile playground for exploring the interaction of electronic correlations and magnetic ordering with the nodal line band topology. Here, we report a detailed electronic band structure investigation of TbSbTe, corroborated by electrical transport, thermodynamic, and magnetic studies. Temperature-dependent magnetic susceptibility and thermodynamic transport studies indicate the onset of antiferromagnetic ordering below TN = 5.1 K. The electronic band structure study, carried out with high-resolution angle-resolved photoemission spectroscopy (ARPES) measurements aided with density functional theory based first-principles calculations reveals presence of nodal lines in the GammaX high symmetry direction, forming a diamond-shaped nodal plane around Gamma high symmetry point. A strongly photon energy dependent nodal feature located at the X point of the surface Brillouin zone, indicating an extended nodal line along X R direction, is also observed. This study elucidates the intricate interplay among symmetry-protected band characteristics, the influence of spin orbit coupling, magnetism, and topological properties.

cond-mat.mes-hall↗

arXiv2025

Electronic band structure of a nodal line semimetal candidate ErSbTe

The LnSbTe family is well known for hosting a plethora of intriguing characteristics stemming from its crystalline symmetry, magnetic structure, 4f electronic correlations and spin orbit coupling (SOC) phenomena. In this paper, we have systematically studied the bulk electrical and thermodynamic properties and electronic structure of the nodal line semimetal candidate ErSbTe using angle resolved photoemission spectroscopy (ARPES) corroborated with first principles based theoretical band structure calculations with and without considering the effect of SOC, a critical factor dictating the band degeneracy which depends on the choice of the Ln atom. Corroborative temperature dependent susceptibility, electrical resistivity and thermodynamic measurements, coherently exhibit paramagnetic to antiferromagnetic phase transition approximately at 1.94 K, and another sharp anomaly at 1.75 K. The zero field cooled resistivity measurement does not show the characteristic hump like feature in the other LnSbTe materials. The electronic band structure of ErSbTe, exhibits a diamond shaped Fermi surface. Along the high symmetry direction GX, electronic bands are projected to cross over the Fermi energy, necessitated by the nonsymmorphic symmetry of the system. The other crossing along this direction is gapped, which evolves along the momentum space reaching its maximum along the GM direction.

cond-mat.mes-hall↗

arXiv2025

Observation of momentum dependent charge density wave gap in EuTe4

The occurrence of charge density wave (CDW) phenomena, particularly in low dimensional rare-earth chalcogenides, has attracted substantial research interest. Among these materials, EuTe4, which features multiple Te layers and a single Eu-Te layer, serves as a promising platform to study the interplay between CDW order and 4f electron configurations, including magnetism. In this study, First principles based density functional theory (DFT) calculations were carried out to investigate the electronic band structure modifications arising from CDW modulation. Angle resolved photoemission spectroscopy (ARPES) revealed the emergence of a CDW gap at the Fermi level, as well as hybridization induced gap features at lower binding energies. The low lying CDW gap reaches its maximum along the Gamma-Y high-symmetry direction and a minimum along GX reflecting the anisotropic nature of the electronic structure. We also performed low temperature heat capacity measurements in applied magnetic fields near the Neel temperature (TN ~ 6.9 K) to construct the magnetic phase diagram of EuTe4. This study provides valuable insight into the directional dependent evolution of the Fermi surface nesting induced CDW ordering, along with other observed gap openings within this system.

cond-mat.mes-hall↗

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

Revealing the intrinsic electronic structure and complex fermiology of YRu2Si2 using angle-resolved photoemission spectroscopy

We performed a detailed study of the intrinsic electronic structure of YRu2Si2 employing angleresolved photoemission spectroscopy (ARPES) and density-functional theory (DFT) based firstprinciples calculations. Electrical and magnetic measurements were conducted on well-oriented highquality single crystals. Bulk physical measurements indicate that the compound exhibits slightly enhanced Pauli paramagnetic behavior, accompanied by electrical transport properties reminiscent of metals. Our ARPES data reveal four fold symmetric Fermi surface with weakly-dispersing bands around the N point originating from Ru d orbitals. We observed the anisotropic characteristics of the band near the N point, showing weak dispersion in the XNX direction and minimal dispersion along the NGN direction. The electronic band structure near the Fermi level is primarily governed by the Ru d orbital, with minor contributions from the Y d and Si p orbitals. Polarization-dependent ARPES results indicate the multi-band and multi-orbital band-character of YRu2Si2. Due to the negligible correlation effect, the observed ARPES data is found to be in good agreement with the DFT results.

cond-mat.mes-hall↗

arXiv2025

Electronic structure in a rare-earth based nodal-line semimetal candidate PrSbTe

Nodal line semimetals feature topologically protected band crossings between the bulk valence and conduction bands that extend along a finite dimension in the form of a line or a loop. While ZrSiS and similar materials have attracted extensive research as hosts for the nodal line semimetallic phase, an alternative avenue has emerged in the form of isostructural rare-earth (RE) based RESbTe materials. Such systems possess intriguing potentialities for harboring elements of magnetic ordering and electronic correlations owing to the presence of 4f electrons intrinsic to the RE elements. In this study, we have carried out angle resolved photoemission spectroscopy (ARPES) and thermodynamic measurements in conjunction with first principles computations on PrSbTe to elucidate its electronic structure and topological characteristics. Magnetic and thermal characterizations indicate the presence of well-localized 4f states with the absence of any discernible phase transition down to 2 K. The ARPES results reveal the presence of gapless Dirac crossings that correspond to a nodal-line along the XR direction in the three-dimensional Brillouin zone. Furthermore, Dirac crossing that makes up nodal line, which forms a diamond-shaped nodal plane centered at the center of the Brillouin zone is also identified within the experimental resolution. This study on the electronic structure of PrSbTe contributes to the understanding of the pivotal role played by spin-orbit coupling in the context of the RESbTe family of materials

cond-mat.mtrl-sci↗