Various magnetism of the compressed antiferromagnetic topological insulator EuSn2As2

TL;DR

This study investigates how high pressure affects the magnetic and electronic properties of EuSn2As2, revealing increased Neel temperatures, persistent negative magnetoresistance, and possible Eu valence changes without structural phase transitions.

Contribution

It provides comprehensive experimental and theoretical insights into pressure-induced magnetic and electronic variations in EuSn2As2, a topological insulator.

Findings

Neel temperature increases from 24 to 77 K under pressure.

Magnetoresistance remains negative at higher temperatures.

Abrupt electronic property changes suggest Eu valence transition.

Abstract

We report a comprehensive high-pressure study on the antiferromagnetic topological insulator EuSn2As2 up to 21.1 GPa through measurements of synchrotron x-ray diffraction, electrical resistance, magnetic resistance, and Hall transports combined with first-principles calculations. No evident trace of a structural phase transition is detected. The Neel temperatures determined from resistance are increased from 24 to 77 K under pressure, which is resulted from the enhanced magnetic exchange couplings between Eu2+ ions yielded by our first-principles calculations. The negative magnetoresistance of EuSn2As2 persists to higher temperatures accordantly. However, the enhancement of the observed N\'eel temperatures deviates from the calculations obviously above 10.0 GPa. In addition, the magnitude of the magnetoresistance, the Hall coefficients, and the charge carrier densities show abrupt changes between 6.9 to 10.0 GPa. The abrupt changes probably originate from a pressure induced valence change of Eu ions from a divalent state to a divalent and trivalent mixed state. Our results provide insights into variation of the magnetism of EuSn2As2 and similar antiferromagnetic topological insulators under pressure.