Emergence of topological superconductivity in the presence of chiral magnetism in 2D CrInTe$_3$

TL;DR

This paper proposes a 2D topological superconductor platform using CrInTe3 monolayers with noncoplanar magnetic textures, inducing Majorana modes and supporting the 2D Kitaev model through a hybrid magnet-superconductor system.

Contribution

It introduces a novel approach to realize 2D topological superconductivity using CrInTe3 monolayers with noncoplanar magnetic textures in a hybrid system.

Findings

CrInTe3 exhibits strong Dzyaloshinskii-Moriya interactions stabilizing spiral magnetic states.

The system supports Majorana zero modes in certain magnetic phases.

Magnetic field induces skyrmions and domain walls, affecting electronic localization.

Abstract

We propose a general framework for designing a two-dimensional (2D) topological superconductor (TSC) using a magnet-superconductor hybrid system. This setup involves a monolayer of CrInTe$_3$, which hosts noncoplanar magnetic textures, in proximity to a 2D $s$-wave superconducting layer. Serving as an alternative to $p$-wave superconductors, this configuration induces a topological superconducting phase and is a promising platform for realizing the 2D Kitaev model, which supports Majorana zero-energy modes through emergent $p$-wave symmetry superconducting pairing. Notably, the magnetic moments break time-reversal symmetry while the superconducting state preserves particle-hole symmetry, placing our system in the Altland-Zirnbauer class $D$ and ensuring robust Majorana excitations. We first perform density functional theory-based simulations to study a monolayer of CrInTe$_3$, from which essential magnetic characteristic parameters, such as Heisenberg exchange interaction and Dzyaloshinskii-Moriya interaction (DMI), are calculated using the state-of-the-art Liechtenstein-Katsnelson-Antropov-Gubanov (LKAG) approach. With a substantial DMI coupling exhibited in CrInTe$_3$, large-scale Monte Carlo simulations reveal the stabilization of a noncoplanar spiral magnetic state as ground state. In this magnetic phase, we observe a transition from corner modes in the zero-energy local density of states (LDOS) to edge modes as the chemical potential ($\mu$) varies. Furthermore, under a finite magnetic field, the system enters a mixed magnetic state, characterized by isolated skyrmions and spiral domain walls, which lead to unique low-energy localization of electronic wave functions, rendering the system an insulator. Finally, we discuss potential experimental realizations of TSC in this magnet-superconductor interfacial system, using real-space probes such as scanning tunneling microscopy (STM).