Prediction of Majorana edge states from magnetized topological surface states

Abstract

As key signatures of topological superconductors (TSCs), the chiral and helical Majorana edge states (MESs) have received increasing attention recently. One prudent mechanism for realizing the MESs is by magnetizing topological surface states (TSSs) associated with conventional superconductivity. Here we construct comprehensive phase diagrams in the parameter space of magnetization and superconductivity for TSSs, based on tight-binding model analyses. In addition to the chiral MESs hosted by the quantum anomalous Hall (QAH), the half-plateau surface QAH and the zero-plateau QAH states, we find that the axion insulator state can realize helical MES, where the opened Zeeman gaps in two TSSs with antiferromagnetic exchange fields eliminate the requirement of the opposite phases between the superconducting gaps in two TSSs. We also demonstrate that the TSC phase is robust against the increase of interaction between two TSSs when the square of the sum of two superconducting gaps is smaller than that of two Zeeman energies. Furthermore, using first-principles approach, we predict MnBi2Te4/Bi2Te3 film placed on a superconducting substrate to be an ideal experimental platform to realize the chiral MESs within a wide energy range (∼80 meV), which persist even down to one quintuple layer of Bi2Te3. Our findings shed light on fundamental understanding of TSC phase and paving another avenue to search for TSC materials.