Magnetism variation of the compressed antiferromagnetic topological insulator EuSn2As2

We report a comprehensive high-pressure study, up to 21.1 GPa, on the antiferromagnetic topological insulator EuSn 2 As 2 achieved through synchrotron X-ray diffraction, Raman scattering, electrical resistance, magnetic resistance, and Hall transport measurements in combination with first-principles calculations. The Néel temperatures determined from resistance are increased from (24±1) to (77±8) K under pressure, which is a result of enhanced magnetic exchange couplings between Eu 2+ ions yielded by our first-principles calculations. The negative magnetoresistance of EuSn 2 As 2 persists to higher temperatures accordingly. However, the enhancement of the observed Néel temperatures deviates from the calculations above 10.0 GPa. In addition, the magnitude of the magnetoresistance, Hall coefficients, and charge carrier densities show abrupt changes between 6.9 and 10.0 GPa. The abrupt changes likely originate from a pressure-induced valence change of Eu ions from a divalent state to a divalent and trivalent mixed state or are related to the structural transition revealed by Raman scattering measurements. Our results provide insight into magnetism variation in EuSn 2 As 2 and similar antiferromagnetic topological insulators under pressure.