Temperature induced itinerant electron metamagnetism in ErCo3 and HoCo3: influence of an external field and pressure

The rhombohedral compounds ErCo3 and HoCo3 order magnetically at 401 and 440 K, respectively. The magnetic properties at low temperatures are characterized by a magnetic instability of their Co-sublattice (metamagnetism) and a spin reorientation in the R-sublattice in HoCo3. These phenomena have been studied by performing specific heat and resistivity measurements. Due to a special balance between the R–Co and Co–Co exchange interactions, a temperature-induced metamagnetic transition in the Co sublattice occurs in the intermetallics ErCo3 (at Tm varying between 65 and 100 K, depending on stoichiometry) and HoCo3 (at Tm=175 K). The application of an external magnetic field (magnetoresistance) and pressure show that the metamagnetic transitions in the Co sublattice are strongly dependent on these parameters (∂Tm/∂P≈−7.5 K/kbar and ∂Tm/∂H=−1.1 K/Tesla).