2025/09/22 by Guopeng Xu, Nemin Wei, Xu, Guopeng +5
Physics and Astronomy · Materials Science · #Topological Materials and Phenomena #Quantum and electron transport phenomena #Graphene research and applications
paper · pdf · doi:10.48550/arxiv.2509.18438
We study Landau-level mixing in a time-reversal-symmetric Hamiltonian composed of two sets of Landau levels with opposite magnetic field, relevant to moiré minibands in twisted homobilayer transition-metal dichalcogenides in the adiabatic limit, where electrons in opposite valleys have flat Chern bands with opposite Chern numbers. Strong spin-orbit coupling polarizes spins in opposite directions in opposite valleys, separating Coulomb interactions into like-spin (V\uparrow\uparrow) and opposite-spin (V\uparrow\downarrow). Using degenerate perturbation theory, we compute Landau-level mixing corrections to V\uparrow\uparrow and V\uparrow\downarrow for different filling fractions. In the lowest Landau level, screening exhibits an even-odd effect: V\uparrow\uparrow is reduced more strongly than V\uparrow\downarrow in even-m angular momentum Haldane pseudopotential and less strongly in odd-m angular momentum ones. In the first Landau level, the short-range part (m=0,1) of V\uparrow\downarrow is reduced comparably to V\uparrow\uparrow, while the strongest spin anisotropy appears in the m=2 pseudopotential. These novel short-range spin correlations have important implications for candidate correlated phases of fractional quantum spin Hall insulators. A distinctive feature of this time-reversal-symmetric Hamiltonian, absent in conventional quantum Hall systems, is that spin-flip excitations form localized quasiparticles. We compute their excitation spectrum and predict a non-monotonic dependence of the ordering temperature of Chern ferromagnetism in MoTe2 on the Landau-level mixing parameter.