Structure, physical properties, and magnetically tunable topological phases in the topological semimetal EuCuBi

A single material achieving multiple topological phases can provide potential application for topological spintronics, whereas the candidate materials are very limited. Here, we report on the structure, physical properties, and possible emergence of multiple topological phases in the recently discovered, air-stable EuCuBi single crystal. EuCuBi crystallizes in hexagonal space group P6(3)/mmc (No. 194) in ZrBeSi-type structure with an antiferromagnetic (AFM) ground state below T-N = 11.2 K. There is a competition between AFM and ferromagnetic (FM) interactions below T-N revealed by electrical resistivity and magnetic susceptibility measurements. With increasing magnetic field, EuCuBi evolves from the AFM ground state with a small amount of FM component, going through a possible metamagnetic phase, finally reaching the field-induced FM phase. Based on the first-principles calculations, we demonstrate that Dirac and Weyl semimetals, and possibly mirror Chern insulators, can be achieved in EuCuBi by tuning the temperature and applying a magnetic field, making EuCuBi a promising candidate for exploring multiple topological phases.