via Synchrotron X-ray Techniques*

Topological materials have attracted significant attention in recent years for their promises in applications of dissipationless electronics. Among these materials, EuSn₂P₂ is a unique topological semimetal [1]. It crystalizes in layered rhombohedral structure, similar to A₂B₃ topological insulators, and orders antiferromagnetically below 30 K. In this work we present systematic high-pressure studies of magnetism in EuSn₂P₂ using synchrotron X-ray diffraction, Moessbauer spectroscopy, X-ray absorption spectroscopy, and molecular orbital calculations. We observed a pressure-induced crystalline to amorphous transition in EuSn₂P₂ at 36 GPa, accompanied by a four-fold enhancement of magnetic ordering temperature attributed by increased RKKY interactions despite gradual Eu²⁺ to Eu³⁺ transition above 20 GPa. This study demonstrates the large tunability in EuSn₂P₂ under pressure, making it an excellent material to study interplay of magnetism, valence, crystal lattice, and topological state.