Coexistence of Ferromagnetism and Topology by Charge Carrier Engineering in intrinsic magnetic topological insulator MnBi4Te7

TL;DR

This paper reports the discovery of a magnetic topological insulator, Mn(Bi0.7Sb0.3)4Te7, exhibiting ferromagnetism and topological surface states, achieved through charge carrier engineering via Sb substitution, advancing the pursuit of high-temperature quantum anomalous Hall effects.

Contribution

The study demonstrates a new intrinsic ferromagnetic topological insulator with tunable magnetic properties through Sb substitution, providing a promising platform for quantum anomalous Hall effect research.

Findings

Mn(Bi0.7Sb0.3)4Te7 exhibits ferromagnetic ground state.

Topological surface states confirmed by ARPES.

Charge carrier engineering modulates magnetism effectively.

Abstract

Intrinsic magnetic topological insulators (MTIs) MnBi2Te4 and MnBi2Te4/(Bi2Te3)n are expected to realize the high-temperature quantum anomalous Hall effect (QAHE) and dissipationless electrical transport. Extensive efforts have been made on this field but there is still lack of ideal MTI candidate with magnetic ordering of ferromagnetic (FM) ground state. Here, we demonstrate a MTI sample of Mn(Bi0.7Sb0.3)4Te7 which holds the coexistence of FM ground state and topological non-triviality. The dramatic modulation of the magnetism is induced by a charge carrier engineering process by the way of Sb substitution in MnBi4Te7 matrix with AFM ordering. The evolution of magnetism in Mn(Bi1-xSbx)4Te7 is systematically investigated by magnetic measurements and theoretical calculations. The clear topological surface states of the FM sample of x = 0.3 are also verified by angle-resolved photoemission spectra. We also aware that the FM sample of x = 0.3 is close to the charge neutral point. Therefore, the demonstration of intrinsic FM-MTI of Mn(Bi0.7Sb0.3)4Te7 in this work sheds light to the further studies of QAHE realization and optimizations.