arXiv subjects

Yaroslav Mudryk

Publications and source records attributed to Yaroslav Mudryk.

At least 19 recordsLinked to original sources

arXiv2026

Breakdown of Anomalous Hall Scaling in Dilute Kondo System

The confluence of strong electronic correlations and Berry curvature-driven transport constitutes a largely underexplored frontier in quantum materials research, particularly in systems where electronic correlations arise from flat-band physics rather than conventional $f$-electron states. Here, we report an intrinsic Berry curvature driven anomalous Hall transport in the dilute Kondo system Ru$_2$Mn$_{0.5}$Ti$_{0.5}$Ge, a non-$f$-electron Heusler alloy hosting flat bands with van Hove singularity proximate to the Fermi level. The anomalous Hall response is strikingly non-monotonic, violating the Fermi-liquid scaling relation near the magnetic transition and is restored only at low temperature, coincident with the onset of Kondo coherence. \textit{Ab initio} calculations strongly establish that the Berry curvature originates from the Kondo hybridization induced interplay of flat bands and spin-orbit coupling mediated anticrossings at the Fermi level. Our findings demonstrate that Kondo coherence of flat bands bears a profound impact on Berry curvature associated ferroic responses, mandating a rigorous theoretical understanding of anomalous transport in the regime where reciprocal space topology and strong correlations are intrinsically intertwined.

cond-mat.str-el↗

arXiv2026

Physical properties of R$_2$Co$_6$Al$_{20-\delta}$ (R = Gd-Tm, Y) single crystals

Rare-earth (R) based intermetallic compounds can often exhibit diverse physical properties and distinct magnetic anisotropies. A Notable example are the light rare earth members of the mono-clinic, R$_2$Co$_6$Al$_{19}$ series that are known to display a range of physical properties, from non-Fermi liquid behavior to antiferromagnetic (AFM) ordering, with properties that vary depending on R. In this work, we have extended this series to the heavy rare earths and systematically investigate the synthesis, crystal structure, and physical properties of single crystals of R$_2$Co$_6$Al$_{20-\delta}$ for R = Gd - Tm and Y. Single crystal X-ray diffraction reveals that these materials adopt an orthorhombic Imma-type structure with delta varying non-monotonically across the heavy rare earths; ranging from 0.73 for Dy to 0.91 for Gd. Temperature-dependent specific heat, resistivity, and magnetization measurements demonstrate AFM ordering in all materials, with the Neel temperature (TN) ranging from 1.8 K for Ho to 11.8 K for Tb. Notably, Gd and Tb-based materials exhibit two distinct AFM transitions, separated by approximately 2 - 3 K. These findings establish the heavy rare-earth members of the R2Co6Al20-delta series as anisotropic antiferromagnets with strong crystal electric field effects and exchange anisotropy. The observed deviation from de Gennes scaling and the anisotropy crossover across the series highlight the important interplay between RKKY exchange and crystal electric field interactions in this orthorhombic system.

cond-mat.mtrl-sci↗

arXiv2026

Metallic d-wave altermagnetism in WFeB: a platform for electrically switchable perpendicular spin-splitter response

We report the synthesis and magnetic characterization of WFeB and identify it as a metallic d-wave altermagnet representative of a broader TiNiSi-type family. Neutron diffraction, Mössbauer spectroscopy, and magnetometry establish a collinear altermagnetic ordering confirmed by first-principles calculations. The electronic structure shows a nonrelativistic spin splitting of approximately 100 meV, but it also supports a strong spin-splitter transport response. This demonstrates that efficient spin-current generation can occur even with such modest band splitting. Symmetry analysis shows that selected film orientations permit deterministic switching of the Néel vector by current-induced staggered torques, enabling electrical control of a perpendicular spin-splitter response. These results establish WFeB and related TiNiSi-type antiferromagnets as a platform for electrically switchable charge-to-spin conversion driven by altermagnetic symmetry.

cond-mat.mtrl-sci↗

arXiv2026

Magnetic field induced modification of a first-order ferromagnetic transition in Eu2In

We present a comprehensive study of the temperature- and magnetic-field-dependent magnetization, specific heat, and local crystal structure across the first-order ferromagnetic-paramagnetic transition in Eu$_2$In. Anomalies in the magnetocaloric response are observed near $H \approx 25$~kOe, including changes in field scaling of magnetic entropy, local entropy exponent, and universal master curve, which suggest an apparent weakening of the first-order character of the transition. However, quantitative analysis of the magnetocaloric parameters together with modified Arrott plots demonstrates that the transition remains first order up to at least 70~kOe. Specific-heat measurements reveal a field-induced splitting of the sharp zero-field anomaly into a doublet, providing a natural explanation for the change in the magnetocaloric response. Magnetic field dependent extended x-ray absorption fine structure (EXAFS) measurements show no detectable field-induced changes in the local coordination environment of Eu. We therefore attribute these observations to a magnetic field induced two-step transition process in Eu$_2$In.

physics.app-ph↗

arXiv2026

Self-thermometry measurements of the adiabatic temperature change in first-order phase transition magnetocaloric materials

Accurately measuring the magnetocaloric effect is necessary to foster the development of magnetic refrigeration devices. However, current methods are inconvenient, requiring different instruments to measure each individual property or a custom-made setup. By measuring the time-varying magnetization in a commercially available VersaLab\textsuperscript{\textregistered} PPMS\textsuperscript{\textregistered} from Quantum Design, we have determined the adiabatic temperature change ($Δ$T$_{\textrm{ad}}$) of the first-order phase transition material Gd$_5$Si$_2$Ge$_2$, for a magnetic field change of 0 to 1 T, under high vacuum ($<$ 0.1 mTorr). For each temperature and magnetic field, the equilibrium magnetization is used as the magnetization-to-temperature conversion curve, allowing us to extend the validity of a previously proposed technique to the first-order phase transition material Gd$_5$Si$_2$Ge$_2$, which exhibits significant hysteresis. Our method thus enables full characterization (magnetic entropy change, adiabatic temperature change, and heat capacity) of any magnetocaloric material, whether it has a first-order or a second-order phase transition, using a single instrument. Comparing to a directly measured $Δ$T$_{\textrm{ad}}$, our method resulted in a peak $Δ$T$_{\textrm{ad}}$ value of 4.47 K, within 1\% of the directly measured value for a sample of the same composition.

cond-mat.mtrl-sci↗

arXiv2026

Rotating Magnetocaloric Effect in First-order Phase Transition Material Gd5Si2Ge2

The rotating magnetocaloric effect (RMCE) induced by self-demagnetization has been investigated in the giant magnetocaloric effect (GMCE) material Gd$_5$Si$_2$Ge$_2$. This shape-dependent effect had thus far only been reported in pure Gd, marking this as the first analysis of the effect in a sample with a magnetostructural first-order phase transition. By rotating the applied magnetic field vector while keeping its intensity constant, the demagnetizing field within a high-aspect ratio sample changes significantly, resulting in a RMCE. We characterize RMCE by determining the adiabatic temperature change ($ΔT_{ad}^{rot}$) directly through temperature measurements, and the isothermal entropy change ($ΔS_M^{rot}$) via magnetometry and magnetostatic simulations. We obtain a remarkable maximum $ΔT_{ad}^{rot}$ of 1.77 K for a constant external field of 0.8 T, higher than that obtained under 1.0 T. The magnetostatic simulations not only corroborate the highly non-monotonous field-dependence of $|ΔS_{M}^{rot}|$, which reaches 95\% of its maximum value at 0.8 T, 6.12 J K$^{-1}$ kg$^{-1}$ for the experimentally measured shape, but also estimate a 35\% increase in the maximum $|ΔS_{M}^{rot}|$ up to 8.67 J K$^{-1}$ kg$^{-1}$ in a simulated shape with higher aspect ratio.

cond-mat.mtrl-sci↗

arXiv2025

From Complex Magnetic Ground States to Magnetocaloric Effects: A Review of Rare Earth R$_2$In Intermetallic Compounds

R2In (R = rare earth) intermetallics exhibit unusual magnetic and magnetocaloric properties, driven by subtle electronic effects, lattice distortions, and spin-lattice coupling. Most of these binary compounds adopt the hexagonal Ni2In-type structure at room temperature, with Eu2In and Yb2In stabilizing in the orthorhombic Co2Si-type lattice. Lighter lanthanide compounds Eu2In, Nd2In, and Pr2In undergo first-order magnetic transitions with negligible hysteresis and minimal lattice volume change and exhibit giant cryogenic magnetocaloric effects, while heavy lanthanide R2In compounds including Gd2In show second-order transitions with moderate magnetocaloric effect. No lanthanide-based R2In compound exhibits symmetry-breaking structural transition, while Y2In transforms from hexagonal to orthorhombic structure near 250 K. Secondary low-temperature transitions, including spin reorientation or antiferromagnetic ordering, further enrich the magnetic phase landscape in these compounds. Integrating theoretical descriptors such as charge-induced strain and electronic structure provides predictive insight into phase stability and magnetocaloric performance, guiding the design of rare-earth intermetallics with tunable magnetic properties for cryogenic applications

cond-mat.mtrl-sci↗

arXiv2025

Theory meets experiment: insights into structure and magnetic properties of Fe$_{1-x}$Ni$_{x}$B alloy

We studied the structural and magnetic properties of the solid solution Fe$_{1-x}$Ni$_{x}$B through theoretical and experimental approaches. Powder X-ray diffraction, X-ray Pair Distribution Function analysis, and energy dispersive X-ray spectroscopy reveal that the Fe$_{1-x}$Ni$_{x}$B solid solution crystallizes in the $β$-FeB structure type up to x = 0.6-0.7 and exhibits anisotropic unit cell volume contraction with increasing Ni concentration. Magnetic measurements showed a transition from ferromagnetism to paramagnetism around x = 0.7. For x = 0.5, the low (< 0.3 $μ_{B}$) magnetic moments suggest itinerant magnetism despite the relatively high Curie temperature (up to 225 K). Theoretical calculations indicated different types of magnetic orderings depending on the Fe/Ni atomic order, with the antiferromagnetic state being stable for ordered FeNiB$_{2}$, whereas the ground state is ferromagnetic for the disordered alloy. Calculations also predicted the coexistence of low- and high-spin states in Fe atoms around the composition with x=0.5, in line with the experimental evidence from $^{57}$Fe Mössbauer spectroscopy. The two magnetically distinct Fe sites for x = 0.3, 0.4, and 0.5 observed by $^{57}$Fe Mössbauer spectroscopy can also be interpreted as two magnetically different regions or clusters that could affect the critical behavior near a quantum magnetic transition based on a potential ferromagnetic quantum critical point identified computationally and experimentally near x=0.64. This work highlights the complex interplay between structure and magnetism in Fe$_{1-x}$Ni$_{x}$B alloys, suggesting areas for future research on quantum critical behavior.

cond-mat.mtrl-sci↗

arXiv2025

Unconventional magnetic glassiness in non-centrosymmetric Sm$_7$Pd$_3$: Interplay of magnetic frustration, long-range order, and frozen domains

We present a comprehensive investigation of the intricate spin dynamics in the non-centrosymmetric compound Sm$_7$Pd$_3$, revealing the coexistence of spin glass, domain glass, and ferromagnetic (FM) behaviors. Magnetic field-dependent measurements indicate large coercivity, suggesting ferromagnetic domain formation below the Curie temperature ($T_C \sim 173$ K), while temperature-dependent magnetization data point to antiferromagnetic (AFM) coupling, highlighting the competition between FM and AFM interactions. Detailed ac susceptibility, isothermal remanent magnetization, and aging effect measurements demonstrate the presence of two distinct types of glassiness in the sample, and their possible origins are discussed extensively. Magnetization measurements reveal the mixing of the J = 5/2 ground state of Sm$^{3+}$ with the excited J = 7/2 multiplet, lying 965 K above. The specific heat data show further crystalline electric field splitting of the J = 5/2 state into a ground-state doublet and a fourfold-degenerate excited state.

cond-mat.mtrl-sci↗

arXiv2025

Fermi surface nesting driven anomalous Hall effect in magnetically frustrated Mn_2PdIn

Noncollinear magnets with near-zero net magnetization and nontrivial bulk electronic topology hold significant promise for spintronic applications, though their scarcity necessitates purposeful design strategies. In this work, we report a topologically nontrivial electronic structure in metallic Mn_2PdIn, which crystallizes in the inverse Heusler structure and exhibits a spin-glassy ground state with quenched magnetization. The system features Weyl-type band crossings near the Fermi level and reveals a novel interplay among momentum-space nesting, orbital hybridization, and spin-orbit coupling. Comprehensive transport measurements uncover a pronounced anomalous Hall effect (AHE) in Mn_2PdIn. The observed quadratic relationship between the longitudinal and anomalous Hall resistivities highlights the intrinsic Berry curvature contribution to AHE. These findings establish inverse Heusler alloys as compelling platforms for realizing noncollinear magnets that host Weyl-type semimetallic or metallic phases-combining suppressed magnetization with robust electronic transport-thereby offering a promising route toward their seamless integration into next-generation spintronic devices.

cond-mat.mtrl-sci↗

arXiv2025

Effects of chemical disorder and spin-orbit coupling on electronic-structure and Fermi-surface topology of YbSb-based monopnictides

In this work, we study the influence of disorder on the electronic structure of YbSb -- a rare-earth monopnictide featuring a simple rock-salt (B1) crystal structure and a well-defined Fermi surface topology -- by employing first-principles density functional theory (DFT). We focus on chemical disorder introduced through Te and Al doping, selected based on their thermodynamic stability in alloyed configurations, to understand how such perturbations modify the electronic states of YbSb. Our results indicate that Te doping predominantly introduces electron-like states at the \textit{X} and \textit{L} points, while Al doping leads to a suppression of hole-like states at $Γ$, effectively driving the system from a semimetallic state to one characterized by very narrow-gap behavior at $Γ$. This modulation of the Fermi surface, particularly the reduction of central hole pockets at $Γ$, plays a central role in altering inter-pocket scattering -- a mechanism critical for tuning quantum transport properties, including superconductivity. This disorder-driven modulation of the Fermi surface, particularly the suppression of central hole pockets at $Γ$, controls inter-pocket scattering, which is essential for optimizing quantum transport properties, including superconductivity. Our results show that disorder can be effectively used as a means of engineering band topology, thereby tuning quantum-related responses through tailored electronic structure.

cond-mat.mtrl-sci↗

arXiv2025

Linking quantum mechanical features to structural phase-transformation in inorganic solids

We present a new descriptor, i.e., local lattice distortion, to predict structural phase transformation in inorganic compounds containing lanthanides and transition metals. The descriptor utilizes local lattice and angular distortions obtained from structural optimization of experimentally known crystalline phases within state-of-the-art density-functional theory method. The predictive power of the descriptor was tested on lanthanide based RE2In (RE=rare-earth) compounds known for a variety of phase transformations. We show that the inclusion of quantum-mechanical effects through local-charge, bonding, symmetry, and electronic-structure enhances the robustness of the descriptor in predicting structural phase transformation. To gain further insights, we analyzed phononic and electronic behavior of Y2In, and show that experimentally observed phase transformation can only be predicted when atomic strains are included. The descriptor was used to predict structural phase change in couple of new compounds, i.e., (Yb1-xErx)2In and Gd2(In1-xAlx), which was validated by X-ray powder diffraction measurements. Finally, we demonstrated the generality of the proposed descriptor by predicting phase transformation behavior in different classes of compounds indicating the usefulness of our approach in mapping desired phase changes in novel functional materials.

cond-mat.mtrl-sci↗

arXiv2025

Unconventional anomalous Hall effect in hexagonal polar magnet Y_3Co_8Sn_4

We report a rare realization of unconventional anomalous Hall effect (UAHE) both below and above the magnetic transition temperature (T_C) in a hexagonal noncentrosymmetric magnet Y_3Co_8Sn_4, using a combined experimental and ab-initio calculations. Occurrence of such UAHE is mainly attributed to the reciprocal (KS) topology (i.e. the presence of topological Weyl points at/near the Fermi level), along with some contribution from the topological magnetic texture, as inferred from the measured field-dependent ac susceptibility. The effect of UAHE on the measured transport behavior however evolves differently with temperature above and below T_C, suggesting different physical mechanism responsible in the two phases. A unique planar ferrimagnetic ordering is found to be the most stable state with ab-plane as the easy plane below TC, as observed experimentally. The simulated net magnetization and the moment per Co atom agrees fairly well with the measured values. A reasonably large AHC is also observed in both the phases (above and below and T_C) of the present compound, which is again not so ubiquitous. Our results underscore the family of R_3Co_8Sn_4 (R= rare earth) polar magnets as a compelling backdrop for exploring the synergy of topological magnetism and non-trivial electronic bands, pivotal for spintronic applications.

cond-mat.mtrl-sci↗

arXiv2024

Large anomalous Hall effect and \textit{A}-phase in hexagonal polar magnet Gd$_3$Ni$_8$Sn$_4$

While recent theoretical studies have positioned noncollinear polar magnets with $C_{nv}$ symmetry as compelling candidates for realizing topological magnetic phases and substantial intrinsic anomalous Hall conductivity, experimental realizations of the same in strongly correlated systems remain rare. Here, we present a large intrinsic anomalous Hall effect and extended topological magnetic ordering in Gd$_3$Ni$_8$Sn$_4$ with hexagonal $C_{6v}$ symmetry. Observation of topological Hall response, corroborated by metamagnetic anomalies in isothermal magnetization, peak/hump features in field-evolution of ac susceptibility and longitudinal resistivity, attests to the stabilization of skyrmion $A$-phase. The anomalous Hall effect is quantitatively accounted for by the intrinsic Berry curvature-mediated mechanism. Our results underscore polar magnets as a promising platform to investigate a plethora of emergent electrodynamic responses rooted in the interplay between magnetism and topology.

cond-mat.str-el↗

arXiv2024

Stability of the first-order character of phase transition in HoCo$_2$

HoCo$_2$ exhibits a giant magnetocaloric (MC) effect at its first-order magnetostructural phase transition around 77~K, and understanding the thermodynamic nature of this transition in response to external magnetic fields is crucial for its MC applications. In this study, we present a comprehensive investigation of specific heat and magnetization measurements of HoCo$_2$ under varying magnetic fields. The specific heat measurements qualitatively indicate a transformation from first- to second-order behavior of this phase transition at higher magnetic fields. However, analysis of the power-law dependence of the magnetic entropy change ($ΔS_{\rm M} \propto$ H$^n$) and the breakdown of universal behavior in the temperature dependence of $ΔS_{\rm M}$ suggest that the first-order nature remains intact, even up to 7 T. This stability of the first-order nature is further manifested through the distinctive non-linear behavior of modified Arrott plots, with a negative slope in the 6--7 T range.

cond-mat.mtrl-sci↗

arXiv2024

The influence of Ga doping on magnetic properties, magnetocaloric effect, and electronic structure of pseudo-binary GdZn1-xGax (x = 0-0.1)

We explore the impact of introducing IIIA-group element Ga in place of IIB-group element Zn in binary intermetallic GdZn on its magnetic and magnetocaloric properties, as well as explicate the modified electronic band structure of the compound. The magnetic transition temperature of the compound decreases with the increase of Ga concentration in GdZn1-xGax (x = 0-0.1) while the crystal structure (CsCl-prototype) and lattice parameters remain unchanged. Our detailed analysis of magnetization and magnetocaloric data conclusively proves that long-ranged magnetic ordering exists in the sample, despite the magnetic interaction considerably weakening with the increase of Ga. The experimental data is rationalized using both theoretical machine learning model and first-principle density functional theory.The electronic band structure of GdZn is manifested with some unusual complex features which gradually diminish with Ga doping and conventional sinusoidal feature of Ruderman-Kittel-Kasuya- Yosida (RKKY)-type interactions also disappears. A mean-field theory model is developed and can successfully describe the overall magnetocaloric behavior of the GdZn1-xGax series of samples

cond-mat.mtrl-sci↗

arXiv2024

Multiple magnetic interactions and large inverse magnetocaloric effect in TbSi and TbSi$_{0.6}$Ge$_{0.4}$

We present a comprehensive investigation of the electronic structure, magnetization, specific heat, and crystallography of TbSi (FeB structure type) and TbSi$_{0.6}$Ge$_{0.4}$ (CrB structure type) compounds. Both TbSi and TbSi$_{0.6}$Ge$_{0.4}$ exhibit two antiferromagnetic (AFM) transitions at T$_{\rm N1}\approx$ 58~K and 57~K, and T$_{\rm N2}\approx$ 36~K and 44~K, respectively, along with an onset of weak metamagnetic-like transition around 6~T between T$_{\rm N1}$ and T$_{\rm N2}$. High-resolution specific heat (C$_{\rm P}$) measurements show the second- and first-order nature of the magnetic transition at T$_{\rm N1}$ and T$_{\rm N2}$, respectively, for both samples. However, in the case of TbSi, the low-temperature (LT) AFM to high-temperature (HT) AFM transition takes place via an additional AFM phase at the intermediate temperature (IT), where both LT to IT AFM and IT to HT AFM phase transitions exhibit a first-order nature. Both TbSi and TbSi$_{0.6}$Ge$_{0.4}$ manifest significant magnetic entropy changes ($ΔS_{\rm M}$) of 9.6 and 11.6~J/kg-K, respectively, for $Δμ_0H$=7~T, at T$_{\rm N2}$. The HT AFM phase of TbSi$_{0.6}$Ge$_{0.4}$ is found to be more susceptible to the external magnetic field, causing a significant broadening in the peaks of $ΔS_{\rm M}$ curves at higher magnetic fields. Temperature and field-dependent specific heat data have been utilized to construct the complex H-T phase diagram of these compounds. Furthermore, temperature-dependent x-ray diffraction measurements demonstrate substantial magnetostriction and anisotropic thermal expansion of the unit cell in both samples.

cond-mat.mtrl-sci↗

arXiv2023

Origin of magnetic ordering in half-Heusler RuMnGa

The half-Heusler alloy RuMnGa having valence electron count (VEC) 18 has recently been theoretically proposed to exhibit compensated ferrimagnetic (CFiM) character instead of the expected nonmagnetic ground state. On the other hand, a preliminary experimental study proposed ferromagnetic (FM) ordering. As no half-Heusler system with VEC 18 is known to exhibit magnetic ordering, we have investigated the details of crystal structure and magnetic properties of RuMnGa using a combination of experimental tools, viz., x-ray and neutron diffraction techniques, dc and ac susceptibility, isothermal magnetisation, heat capacity, resistivity and neutron depolarisation measurements. Rietveld refinements of x-ray and neutron diffraction data suggest single phase nature of the compound with elemental composition RuMn$_{0.86}$Ga$_{1.14}$. We have shown that the system exhibits FM-type ordering owing to the inherent presence of this minor off-stoichiometry, showing very low magnetic moment. The system also exhibits reentrant canonical spin-glass behaviour, which is rarely observed in half-Heusler alloys. The temperature coefficient of resistivity changes its sign from negative to positive and further to negative as the temperature decreases.

cond-mat.mtrl-sci↗