Itinerant metamagnetic transition in the ferromagnet LuCo₃ induced by high field: Instability of the 3d-electron subsystem

LuCo₃ is an itinerant ferromagnet whose magnetic properties strongly depend on the position of the 3d electronic states relative to the Fermi level. Here, we report on the magnetization of a LuCo₃ single crystal in pulsed magnetic fields up to 58 T. We find a field-induced phase transition just below 50 T from a low-spin to a high-spin state. The transition shows a pronounced anisotropy of the magnetization jump and hysteresis. A series of ab initio calculations based on the density functional theory show that the transition is due to a significant change in the occupancies of the Co 3d electronic states. At the same time, some features in the majority spin density of the Co 3d states are slightly modified and pass through the Fermi level when the spin state is changed, which leads to the instability of the 3d-electron subsystem. Thereby, the applied magnetic field causes a significant redistribution in the majority and minority spin states in the Co 3d subsystem, which results in the sharp change in the magnetization.