Unusual Room Temperature Ferromagnetism in Bulk Sintered GaP Doped with Copper

Robust room temperature ferromagnetism is obtained in single phase Gallium Phosphide doped with Cu²⁺ prepared by simple solid state reaction route. The saturation magnetization at 300 K is 1.5times10^-2 emu/g and the coercivity was found to be 125 Oe. A strong ferromagnetic resonance signal confirms the long range magnetic order which persists to temperatures as high as 739 K. X-ray absorption spectroscopy (XAS) indicate that Cu is in a +2 state. Ab initio calculations also show that the ferromagnetic ordering is energetically favorable in Cu doped GaP. When the spin-orbit coupling is included we get an enhanced total magnetic moment of 0.31 muB with a local moment on Cu 0.082 and on P 0.204 mu_B. per atom