Temperature-pressure phase diagram of the intrinsically insulating topological antiferromagnet EuCd2As2

Zintl-phase EuCd2As2 attracts much research interest because it has a potential of manifesting various ideal topological states under external parameters. Here, measurements of resistance, magnetization, Hall, and synchrotron x-ray diffraction at high pressures up to 50.8 GPa in diamond anvil cells are performed on high-quality EuCd2As2 single crystals that display a long-sought intrinsically insulating antiferromagnetic (AFM) ground state. From ambient pressure to 21.0 GPa, the AFM state of EuCd2As2 is stable and the AFM transition temperature of -9.5 K is raised linearly at a rate of -1.90 K/GPa. Meanwhile, the insulating conduction behavior is maintained despite that the whole resistance decreases remarkably. Beyond -24.0 GPa, a ferromagnetic-like metallic state shows up, due to a trigonal P3m1 to monoclinic C2/m structural transition, and its transition temperature of -150 K increases linearly at a rate of -0.69 K/GPa. This high-pressure magnetic metallic state dominates over the pristine AFM insulating one upon completion of the structural transition around 40 GPa. Based on the present data, we construct a temperature-pressure phase diagram for the intrinsically insulating antiferromagnet EuCd2As2, which offers essential insights into the pressure-dependent evolutions of magnetic and transport properties and will stimulate further exploration of the interplay among magnetism and transport, as well as nontrivial topology rooted in their interactions.