arXiv subjects

Grigorii Skorupskii

Publications and source records attributed to Grigorii Skorupskii.

6 recordsLinked to original sources

arXiv2026

2D Theoretically Twistable Material Database

The study of twisted two-dimensional (2D) materials, where twisting layers create moiré superlattices, has created opportunities for investigating topological phases and strongly correlated physics. The broader potential of a seemingly infinite set of twistable 2D materials remains largely unexplored. Here, we define ''theoretically twistable materials'' as single- or multi-layer structures that allow for the construction of simple continuum models of their moiré structures. Our high-throughput algorithm systematically searches for theoretically twistable semimetals and insulators based on the Topological 2D Materials Database (2D-TQCDB). By analyzing key electronic properties, we identify thousands of candidate materials, propose representative twistable materials, and provide examples of crystal growth and exfoliation for several of them. Our results provide a resource for future experimental and theoretical studies of moiré systems.

cond-mat.mtrl-sci↗

arXiv2026

New Superconductors in the PtPb$_3$Bi Structure Type

The quest for new superconductors is of both fundamental and technological importance. Recently, an artificial intelligence method correctly predicted PtPb$_3$Bi to be a superconductor. In this work, we find superconductivity in the newly synthesized $M$Pb$_{4-x}$Bi$_x$ ($M$ = Au, Pd, and Rh), of which PtPb$_3$Bi is a member. When $M$ = Ni, whose radius is considerably smaller, the structure instead collapses into the different, Pb-substituted NiBi$_3$ type. Interestingly, the stoichiometric parameter $x$ shifts across the three compounds to keep the total valence electron count close to 20 per formula unit. The superconducting transitions occur at 4.9, 4.2, and 3.4 K, for $M$ = Au, Pd, and Rh, respectively. Using electrical resistivity, magnetization, and specific heat measurements, we establish the bulk nature of the superconducting state and determine the critical fields, characteristic length scales, and anisotropy ratios. All three compounds are moderately anisotropic type-II superconductors, with modest upper critical field anisotropies of $H_{c2}^{\parallel c}/H_{c2}^{\perp c} \approx 1.2$ to $1.5$. These results establish $M$Pb$_{4-x}$Bi$_x$ as a family of anisotropic superconductors and a platform for studying how site disorder and Pb-Bi mixing govern superconductivity in heavy-element intermetallics.

cond-mat.supr-con↗

arXiv2026

New Crystal Structures Hide in Plain Sight: A Stress Test for AI-Guided Materials Discovery

New types of crystal structures are discovered only rarely, and the artificial intelligence (AI) models now reshaping materials discovery have so far produced new chemical compositions within known structural families rather than genuinely new structures. We report GdNiSn4 and LuNiSn4, intermetallics that adopt a previously unreported structure type, found not by computation but by exploratory synthesis. Single-crystal diffraction shows that the structure is an intergrowth of two known structural units. We then use this system as a benchmark for two leading generative models, MatterGen and DiffCSP++. For DiffCSP++, the benchmark is performed in its crystallographically constrained setting, using the required space-group and Wyckoff-position inputs. Under our sampling budget, neither model recovers the experimentally reported monoclinic structure within the structural-matching tolerance. The generated structures are evaluated without further structural relaxation using the nonmagnetic analog LuNiSn4, where we rule out 4f magnetism as the cause. Because the new structure is built from familiar building blocks, it should be derivable. We argue that encoding chemical reasoning, such as the stacking of known motifs, is a concrete path toward AI that can discover structurally novel materials.

cond-mat.mtrl-sci↗

arXiv2026

Measuring the Hall effect in hysteretic materials

Measurement of the Hall effect is a ubiquitous probe for materials discovery, characterization, and metrology. Inherent to the Hall measurement geometry, the measured signal is often contaminated by unwanted contributions, so the data must be processed to isolate the Hall response. The standard approach invokes Onsager-Casimir reciprocity and antisymmetrizes the raw signal about zero applied magnetic field. In hysteretic materials this becomes nontrivial, since Onsager-Casimir relations apply only to microscopically reversible states. Incorrect antisymmetrization can lead to artifacts that mimic anomalous or topological Hall signatures. The situation is especially subtle when hysteresis loops are not centered at zero applied field, as in exchange-biased systems. A practical reference for generically extracting the Hall response in hysteretic materials is lacking. Here, using Co$_3$Sn$_2$S$_2$ as a bulk single-crystal model that can be prepared with or without exchange-biased hysteresis, we demonstrate two procedures that can be used to extract the Hall effect: (1) reverse-magnetic-field reciprocity and (2) antisymmetrization with respect to applied field. We then measure the Hall effect on CeCoGe$_3$, a noncentrosymmetric antiferromagnet which can be prepared to have asymmetric magnetization and magnetoresistance, and demonstrate how improper processing can generate artificial anomalous Hall signals. These methods are generic and can be applied to any conductor.

cond-mat.str-el↗

arXiv2026

Tunable magnetotransport through kinetically hindered first-order phase transitions in an antiferromagnetic metal

Controllable multilevel resistance states are of interest for memory technologies like neuromorphic computing, but robust materials platforms toward such behavior remain limited. Here, we show that the non-centrosymmetric antiferromagnetic metal CeCoGe$_3$ suggests one such route through a kinetically hindered first-order magnetic transition. Cooling through the kinetically hindered first-order transition in an applied magnetic field produces a magnetic glass state in which high- and low-temperature magnetic phases coexist. The relative fraction of these phases can be controlled by the applied field in which the sample is cooled, and the electrical resistance is directly sensitive to that fraction. As a result, it is demonstrated that CeCoGe$_3$ supports stable multilevel resistive states. These results identify kinetically hindered first-order phase transitions as a promising route towards controllable multilevel magnetoresistive states.

cond-mat.str-el↗

arXiv2017

Rapid and Precise Determination of Zero-Field Splittings by Terahertz Time-Domain Electron Paramagnetic Resonance Spectroscopy

Zero-field splitting (ZFS) parameters are fundamentally tied to the geometries of metal ion complexes. Despite their critical importance for understanding the magnetism and spectroscopy of metal complexes, they are not routinely available through general laboratory-based techniques, and are often inferred from magnetism data. Here we demonstrate a simple tabletop experimental approach that enables direct and reliable determination of ZFS parameters in the terahertz (THz) regime. We report time-domain measurements of electron paramagnetic resonance (EPR) signals associated with THz-frequency ZFSs in molecular complexes containing high-spin transition-metal ions. We measure the temporal profiles of the free-induction decays of spin resonances in the complexes at zero and nonzero external magnetic fields, and we derive the EPR spectra via numerical Fourier transformation of the time-domain signals. In most cases, absolute values of the ZFS parameters are extracted from the measured zero-field EPR frequencies, and the signs can be determined by zero-field measurements at two different temperatures. Field-dependent EPR measurements further allow refined determination of the ZFS parameters and access to the g-factor. The results show good agreement with those obtained by other methods. The simplicity of the method portends wide applicability in chemistry, biology and material science.

physics.chem-ph↗