Suppression of the antiferromagnetic metallic state in the pressurized MnBi2Te4 single crystal

TL;DR

This study investigates how hydrostatic pressure affects the magnetic and electronic properties of MnBi2Te4, revealing suppression of antiferromagnetic order and a transition from metallic to insulating behavior, with no structural change up to high pressures.

Contribution

It provides new insights into pressure-induced magnetic and electronic phase transitions in MnBi2Te4, combining experimental transport measurements and first-principles calculations.

Findings

Antiferromagnetic transition temperature first increases then decreases with pressure.

Resistivity evolves from metallic to activated behavior as AF order is suppressed.

Carrier density increases under pressure, with no structural phase transition up to 12.8 GPa.

Abstract

MnBi2Te4 has attracted tremendous research interest recently as the first intrinsic antiferromagnetic (AF) topological insulator. It undergoes a long-range AF order at TN = 24 K accompanied with a cusp-like anomaly in the metallic resistivity. Here, we studied the effect of hydrostatic pressure on its electrical transport properties up to 12.5 GPa by using a cubic anvil cell apparatus. We find that TN determined from the resistivity anomaly first increases slightly with pressure and then decreases until vanished completely at ~7 GPa. Intriguingly, its resistivity rho(T) is enhanced gradually by pressure, and evolves from metallic to activated behavior as the AF order is suppressed. From the Hall resistivity measurements, we confirm that the n-type carriers dominate the transport properties and the carrier density is raised by pressure. In addition, the critical magnetic field Hc1 ~3.3 T at 0 GPa for the spin-flop transition to the canted AF state is found to increase to ~ 5 T and 7.5 T at 1 and 3 GPa. High-pressure XRD evidenced no structural transition up to 12.8 GPa. Based on the Hall resistivity results and first-principles calculations, we proposed that the intralayer direct AF interactions are strengthened by pressure and the competition between AF and FM interactions not only prevents long-range magnetic order but also promotes charge carrier localizations through enhance magnetic fluctuations at high pressures.