Pressure-Induced Changes in Structure, Magnetic Order and Development of Superconductivity in the Ferromagnetic Topological Insulator MnBi8Te13

TL;DR

This study explores how applying pressure to MnBi8Te13 induces magnetic phase transitions and superconductivity, revealing a complex interplay between magnetism and superconductivity in a topological insulator.

Contribution

It provides the first detailed phase diagram showing pressure-induced magnetic and superconducting transitions in MnBi8Te13, highlighting the role of Mn concentration.

Findings

Pressure suppresses ferromagnetism and induces antiferromagnetism.

Superconductivity emerges above 16.6 GPa with a maximum Tc of 6.8 K.

MnBi6Te10 shows no superconductivity up to 40 GPa.

Abstract

We report a comprehensive study of pressure-induced evolution of the magnetism and development of superconductivity (SC) in MnBi8Te13, a promising ambient pressure, ferromagnetic (FM) topological insulator candidate. By employing high-pressure electrical transport, magnetoresistance, DC magnetic susceptibility, and X-ray diffraction measurements, we construct a detailed temperature-pressure phase diagram. At ambient pressure, MnBi8Te13 exhibits FM ordering with an easy-axis along the c-axis which is progressively suppressed under pressure and replaced by an antiferromagnetic (AFM) order. Density functional theory calculations predicted an evolution from FM to a G-type AFMg2 phase near 5 GPa. Above 16.6 GPa, a bulk SC state emerges with a maximum transition temperature ~6.8 K, as confirmed by resistance and magnetic susceptibility measurements. This pressure-induced SC may co-exist with another AFM dome that shows a weak anomaly in the transport data. In contrast, our work on MnBi6Te10 shows no SC up to 40 GPa. Indeed, in contrast to MnBi8Te13, the MnBi2Te4(Bi2Te3)n compounds with n < 3, didn't exhibit SC, highlighting the crucial role of Mn concentration in stabilizing SC. The observation of pressure-induced FM-AFM-SC transitions in MnBi8Te13 not only establishes it as a rare Mn-based SC but also provides a platform to study the interplay between magnetism, SC, and potentially nontrivial band topology in correlated magnetic materials.