arXiv subjects

Erekle Jmukhadze

Publications and source records attributed to Erekle Jmukhadze.

3 recordsLinked to original sources

arXiv2026

Stripe antiferromagnetism and chiral superconductivity in tWSe$_2$

The layer-dependent Hamiltonians of parallel-stacked MoTe$_2$ and WSe$_2$ homobilayer moiré materials are topologically non-trivial, both in real space and in momentum space, and have been shown to support integer and fractional quantum anomalous Hall states, as well as antiferromagnetic and superconducting states. Here, we address the interplay between the antiferromagnetic and superconducting states observed in tWSe$_2$ when the Fermi level is close to its $M$-point van Hove singularity and the displacement field is small. We combine DFT with path-integrals to construct a minimal moiré band model that accounts for lattice relaxation along the $c$-axis and perform Hartree-Fock calculations to identify competing charge and spin ordered states. For tWSe$_2$ at $θ=2.7^\circ$ and $θ=3.65^\circ$, we find that a layer antiferromagnet (AFM), a stripe spin-density-wave (SDW), and the ferromagnetic Chern insulator (FM) are the primary candidates for the ground state at zero displacement field, and argue that antiferromagnetic spin interactions on the next neighbor bond $J_2$ can induce a time-reversal symmetry breaking chiral superconducting 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↗

arXiv2023

Ab-initio study of the energy competition between Γand K valleys in bilayer transition metal dichalcogenides

Moiré engineering in two-dimensional van der Waals bilayer crystals has emerged as a flexible platform for controlling strongly correlated electron systems. The competition between valleys for the band extremum energy position in the parent layers is crucial in deciding the qualitative nature of the moiré Hamiltonian since it controls the physics of the moiré minibands. Here we use density functional theory to examine the competition between K and $Γ$ for the valence band maximum in homo- and hetero-bilayers formed from the transition metal dichalcogenides (TMD), MX\{_2} where M=Mo,W and X=S,Se,Te. We shed light on how the competition is influenced by interlayer separation, which can be modified by applying pressure, by external gate-defined electric fields, and by transition metal atom d-orbital correlations. Our findings are related to several recent experiments, and contribute to the development of design rules for moiré materials.

cond-mat.mtrl-sci↗