Electrical resistivity of ErB₂ under pressure

Diborides A B 2 crystallizing in the hexagonal C32 structure exhibit a wide range of magnetic and electronic properties depending on the choice of the element A and the precise values of the lattice constants a and c. ErB₂ represents a typical rare-earth diboride, exhibiting easy-plane ferromagnetic order below 14 K. We report a study of the evolution of the electrical transport properties of ErB₂ when tuning the lattice constants under pressures up to 5.6 GPa. Using Bridgman-type pressure cells with polycrystalline diamond anvils and steatite as the solid pressure medium, quasi-hydrostatic conditions are provided. We find that magnetic order is stabilized under pressure and discuss the influence of uniaxial components by comparing measurements on polycrystalline and single-crystalline samples.