arXiv subjects

Jan Skolimowski

Publications and source records attributed to Jan Skolimowski.

14 recordsLinked to original sources

arXiv2026

Interplay between Relativistic Spin-Momentum Locking and Breaking of Inversion Symmetry: conditions for p-wave magnetism

We investigate the interplay between relativistic spin-momentum locking arising from altermagnetism and various forms of inversion symmetry breaking. Depending on the symmetry breaking, this can give rise to Rashba-type spin-orbit coupling (SOC), Weyl-type SOC, or the coexistence of two distinct spin-momentum lockings. We focus on the altermagnetic Ca2RuO4 as a testbed material. Our results reproduce the experimentally observed ground state, which is an A-centered magnetic order with the Neel vector along the b-axis, hosting spin cantings along the a- and c-axes but without weak ferromagnetism. Ca2RuO4 exhibits relativistic spin-momentum locking, with different even-parity wave orders for the three spin components. We interpret the experimental results on doped samples as evidence for a transition from a pure altermagnetic phase to a weak ferromagnetic phase. Under ferroelectric- and antiferroelectric-like distortions, there are no qualitative changes in the non-relativistic spin-momentum locking and in the weak ferromagnetism. However, we observe the rise of the Rashba or Weyl-type SOC. Using numerical and analytical models, we investigate which nodal planes persist when inversion symmetry is broken in the relativistic case. The spin-momentum locking of the other components adopt a p-wave character in the case of Rashba; in contrast, Weyl-type SOC disrupts all nodal planes, leaving only nodal lines. Finally, to simulate a stripe phase with structural distortions along the z-axis, we studied a modulated electric field inducing atomic displacements within one Ca2RuO4 layer. This produces a magnetic phase transition to an exotic altermagnetic state with two non-relativistic spin-momentum lockings hosting weak ferromagnetism. Our research presents a comprehensive analysis of various possible scenarios in altermagnets with breaking of inversion symmetries under relativistic effects

cond-mat.mtrl-sci↗

arXiv2026

Staggered Dzyaloshinskii-Moriya and canting angle in centrosymmetric altermagnetic and ferromagnetic phases: influence on the anomalous Hall effect and Weyl points

We present a simple methodology to compute the anomalous Hall conductivity (AHC) as a function of the canting angles in ferromagnets and altermagnets, starting from a nonmagnetic Hamiltonian obtained from first-principles calculations that preserves the full symmetry of the crystal structure. Magnetism is introduced by including on-site spin splitting, spin-orbit coupling, and spin-canting angles. As a representative material, we study SrRuO$_3$, which supports spin canting and exhibits a sign change of the AHC. In the ferromagnetic phase, the low-energy AHC is found to be close to zero at the Fermi level, in agreement with experimental observations. We show that the dependence of the AHC on the relevant physical parameters is most pronounced in the central region of the electronic bandwidth. We determine the symmetry-allowed components of the AHC for different magnetic orders in the large family of transition-metal perovskite ABO$_3$ compounds with space group $62$, including the spontaneous in-plane anomalous Hall effect. Within density functional theory, we evaluate the range of spin-canting angles in SrRuO$_3$ and demonstrate that it is suppressed as electronic correlations increase. By analyzing the AHC as a function of the canting angle, we find that the collinear magnetic configurations contribute most to the AHC, while spin canting plays a secondary role in determining its magnitude in non-collinear ferromagnets and altermagnets. However, canting can become relevant and induce a sign change of the AHC when the collinear magnetic state exhibits an AHC close to zero. Finally, we investigate the locations of Weyl points in the Brillouin zone and their evolution as a function of the canting angle.

cond-mat.mtrl-sci↗

arXiv2025

Dual topology and edge-reconstruction in $α$-Sn

We formulate the tight-binding model for cubic $α$-Sn based on the DFT calculations. In the model, we incorporate a variable bond angle, which allows us to simulate the effect of the in-plane strain. In the bulk, we demonstrate the presence of the $\mathbb{Z}_2$ topological invariant and a non-zero mirror Chern number, making $α$-Sn one of the rare cases where dual topology can be observed. We calculate the topological phase diagram of multi-layer $α$-Sn as a function of strain and number of layers. We find that a non-trivial quantum spin Hall state appears only for compressive strain above five layers of thickness. Quite surprisingly, both in the trivial and non-trivial phases, we find a plethora of edge-states with energies inside the bulk gap of the system. Some of these states are localized at the side surfaces of the slab, some of them prefer top/bottom surfaces and some are localized in the hinges. We trace the microscopic origin of these states back to a minimal model that supports chiral symmetry and multiple one-dimensional winding numbers that take different values in different directions in the Brillouin zone.

cond-mat.mes-hall↗

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

Fate of gapless edge states in two-dimensional topological insulators with Hatsugai-Kohmoto interaction

Topologically protected edge states are the highlight feature of an interface between non-equivalent insulators. The robustness/sensitivity of these states to local single-particle perturbations is well understood, while their stability in the presence of various types of two-particle interactions remains unclear. To add to previous discussions of the Hubbard and unscreened Coulomb interactions, we address this problem from the point of view of infinite-range Hatsugai-Kohmoto interaction. Based on our numerical results for two models of Chern insulators, the Kane-Mele and spinful Haldane model, on a ribbon geometry with zig-zag edges, we argue that any finite interaction strength $U$ is sufficient to open a charge gap in the spectrum of either Chern insulator. We explain the differences between the two cases and present how their edge states phase out as the system enters the strongly correlated phase. We show that the closing of the many-body gap in periodic variants of these models can be connected to the onset of hybridization between the edge and bulk modes in finite geometries. Providing an example of the bulk-boundary correspondence in systems where there is a topological phase transition without closing of the spectral gap.

cond-mat.str-el↗

arXiv2024

Real-space analysis of Hatsugai-Kohmoto interaction

The Hatsugai-Kohmoto interaction model has gained a lot of attention in recent years, due to the fact it is exactly solvable in momentum space in any dimension while capturing some key features of the Mott phase. Here a one-dimensional lattice model with this interaction is approached from the real-space perspective, to explore how breaking the translation invariance of a lattice affects the intuition built by studying the exact solution in $k$-space. The ground state properties of chains with periodic and open boundary conditions are calculated and compared with both the exact solution in momentum space, as well as with analogous solutions of the Hubbard model. The results show that introducing hard edges enhances the ferromagnetic correlations and the system undergoes a magnetic transition before reaching the strong coupling limit. Understanding the impact of hard edges is a crucial step toward answering the looming question of the existence of edge states and other topological phenomena in systems with this type of interaction.

cond-mat.str-el↗

arXiv2024

Impact of correlations on topology in Kane-Mele model decorated with impurities

We propose an effective model for the study of the interplay between correlation and topology by decorating the Kane-Mele model with a set of localized interacting orbitals hybridized to just one sublattice, breaking the inversion symmetry. We show that in the time-reversal symmetric case, the interplay between interactions and hybridization extends the stability of the topological phase and depending on the driving mechanism very different behaviors are observed after the topological phase transition (TPT). We discuss the fate of the TPT in presence of weak ferromagnetic order, by introducing a weak local magnetic field at the localized orbitals, which splits the two band inversion points. One of the platforms to apply this model to are ferrovalley compounds, which are characterized by two independent band inversion points. Understanding this family of materials is crucial for the development of the valleytronics. An alternative to spintronics, which uses valley polarization as opposed to spin degrees of freedom as the building block, promises great opportunities for the development of information storage.

cond-mat.str-el↗

arXiv2023

Topological Mott insulator in the odd-integer filled Anderson lattice model with Hatsugai-Kohmoto interactions

Recently, a quantum anomalous Hall state at odd integer filling in moiré stacked MoTe$_2$/WSe$_2$ was convincingly interpreted as a topological Mott insulator state appearing due to strong interactions in {\it band} basis [P. Mai, J. Zhao, B. E. Feldman, and P. W. Phillips, Nat. Commun. {\bf 14}, 5999 (2023)]. In this work, we aim to analyze the formation of a topological Mott insulator due to interactions in {\it orbital} basis instead, being more natural for systems where interactions originate from the character of $f$ or $d$ orbitals rather than band flatness. For that reason, we study an odd-integer filled Anderson lattice model incorporating odd-parity hybridization between orbitals with different degrees of correlations introduced in the Hatsugai-Kohmoto spirit. We demonstrate that a topological Mott insulating state can be realized in a considered model only when weak intra- and inter-orbital correlations involving dispersive states are taken into account. Interestingly, we find that all topological transitions between trivial and topological Mott insulating phases are not accompanied by a spectral gap closing, consistent with a phenomenon called {\it first-order topological transition}. Instead, they are signaled by a kink developed in spectral function at one of the time reversal invariant momenta. We believe that our approach can provide insightful phenomenology of topological Mott insulators in spin-orbit coupled $f$ or $d$ electron systems.

cond-mat.str-el↗

arXiv2023

Orbital-selective altermagnetism and correlation-enhanced spin-splitting in transition metal oxides

We investigate the altermagnetic properties of strongly-correlated transition metal oxides considering the family of the quasi two-dimensional A2BO4 and three-dimensional ABO3. As a test study, we analyze the Mott insulators Ca2RuO4 and YVO3. In both cases, the orbital physics is extremely relevant in the t2g subsector with the presence of an orbital-selective Mott physics in the first case and of a robust orbital-order in the second case. Using first-principles calculations, we show the presence of an orbital-selective altermagnetism in the case of Ca2RuO4. In the case of YVO3, we study the altermagnetism as a function of the magnetic ordering and of the Coulomb repulsion U. We find that the altermagnetism is present in all magnetic orders with the symmetries of the Brillouin zone depending on the magnetic order. Finally, the Coulomb repulsion enhances the non-relativistic spin-splitting making the strongly-correlated systems an exciting playground for the study of the altermagnetism.

cond-mat.str-el↗

arXiv2022

Impurities and other defects in correlated lattice electrons: Friedel oscillations and interference patterns

We study interference patterns and Friedel oscillations (FO) due to scattering from two or more localized impurities and scattering from extended inhomogeneities in the two-dimensional lattice systems of interacting fermions. Correlations between particles are accounted for by using an approximate method based on the real-space dynamical mean-field theory and a homogeneous self-energy approximation (HSEA), where the site-dependent part of the self-energy is neglected. We find that the interference maxima and minima change systematically as we vary the relative distance between the two impurities. At the same time, the increase of the interaction does not shift the position of interference fringes but only reduces their intensities. A comparison with the single impurity cases clearly shows complex patterns in FO fringes induced by additional multiple scattering processes. In the case of an extended step like potential the system becomes more homogeneous when the interaction increases. FO and interference patterns are not present in the Mott insulating phase in both single and many impurity models.

cond-mat.str-el↗

arXiv2022

Interplay between edge states and charge density wave order in the Falicov-Kimball model on a Haldane ribbon

To determine the impact of including edge states on the phase diagram of a spinless Falicov-Kimball model (FKM) on the Haldane lattice, a study of a corresponding ribbon geometry with zigzag edges is conducted. By varying the ribbon widths, the distinction between the effects connected to the mere presence of the edges and those originating from interference between the edge states is established. The local doping caused by the former is shown to give rise to a topologically trivial bulk insulator with metallic edge states. Additionally, it gives rise to a charge density wave (CDW) phase with mixed character of the subbands in various parts of the phase diagram. The local doping on the CDW instability is also addressed. Two additional gapless phases are found, caused by the edges but with stability regions depending on the width of the ribbon.

cond-mat.str-el↗

arXiv2022

Luttinger's theorem in presence of Luttinger surfaces

Breakdown of Landau's hypothesis of adiabatic continuation from non-interacting to fully interacting electrons is commonly believed to bring about a violation of Luttinger's theorem. Here, we elucidate what may go wrong in the proof of Luttinger's theorem. The analysis provides a simple way to correct Luttinger's expression of the electron number in single-band models where perturbation theory breaks down through the birth of a Luttinger surface without symmetry breaking. In those cases, we find that the Fermi volume only accounts for the doping away from half-filling. In the hypothetical circumstance of a non-symmetry breaking Mott insulator with a Luttinger surface, our analysis predicts the noteworthy existence of quasiparticles whose `Fermi` surface is just the Luttinger one. Therefore, those quasiparticles can be legitimately regarded as `spinons`, and the Mott insulator with a Luttinger surface as realisation of a spin-liquid insulator.

cond-mat.str-el↗

arXiv2019

The perils of minimal coupling to electromagnetic field in quantum many-body systems

Consistency with the Maxwell equations determines how matter must be coupled to the electro-magnetic field (EMF) within the minimal coupling scheme. Specifically, if the Hamiltonian includes just a short-range repulsion among the conduction electrons, as is commonly the case for models of correlated metals, those electrons must be coupled to the full internal EMF, whose longitudinal and transverse components are self-consistently related to the electron charge and current densities through Gauss's and circuital laws, respectively. Since such self-consistency relation is hard to implement when modelling the non-equilibrium dynamics caused by the EMF, as in pump-probe experiments, it is common to replace in model calculations the internal EMF by the external one. Here we show that such replacement may be extremely dangerous, especially when the frequency of the external EMF is below the intra-band plasma edge.

cond-mat.str-el↗

arXiv2018

Mottness collapse without metallisation in the domain walls of triangular-lattice Mott insulator 1T-TaS$_2$

1T-TaS$_2$ is a charge-density-wave (CDW) compound with a Mott-insulating ground state. The metallic state obtained by doping, substitution or pulsed charge injection is characterized by an emergent CDW domain wall network, while single domain walls can be found in the pristine Mott state. Here we study whether and how the single walls become metallic. Tunneling spectroscopy reveals partial suppression of the Mott gap and the presence of in-gap states strongly localized at the domain-wall sites. Using the real-space dynamical mean field theory description of the strongly correlated quantum-paramagnet ground state we show that the local gap suppression follows from the increased hopping along the connected zig-zag chain of lattice sites forming the domain wall, and that full metallisation is preempted by the splitting of the quasiparticle band into bonding and antibonding sub-bands due to the structural dimerization of the wall, explaining the presence of the in-gap states and the low density of states at the Fermi level.

cond-mat.str-el↗