High-Temperature Majorana Corner States

Majorana bound states often occur at the end of 1D topological superconductor or at the $\pi$ Josephson junction mediated by a helical edge state. Validated by a new bulk invariant and an intuitive edge argument, we show the emergence of one Majorana Kramers pair at each corner of a square-shaped 2D topological insulator proximitized by an $s_\pm$-wave (e.g., Fe-based) superconductor. We obtain a phase diagram that emphasizes the roles of bulk parameters and edge orientations. We propose several experimental realizations in lattice-matched candidate materials. Our scheme offers a high-temperature platform for exploring higher-order non-Abelian quasiparticles.