Metamagnetism of RCo2 compounds

Abstract

Self-consistent spin-polarized energy-band calculations are reported for the RCo2 compounds (R=Tb-Yb). By changing the magnitude of the 4f spin in GdCo2 from zero to seven and back to zero, hysteresis was obtained with both low- and high-moment conduction-electron states being obtained for spin less than 4. For the real compounds, when the calculations were started with no moment on the Co, low-conduction-electron moments were obtained for DyCo2-YbCo2. However, when the calculations were started with large moments on the Co the total conduction-electron moments were calculated to be 1.75 μB/f.u. for all of the compounds. It is suggested that the conduction-electron-state densities in all of the compounds are similar to those in YCo2 and LuCo2 and that the conduction-band system is essentially metamagnetic.