Optical properties of the half-metallic La3/4Ca1/4MnO3

We studied the electronic structure and optical properties of the low tempe rature (T = 0 K for the calculation) ferromagnetic phase of La3/4Ca1/4MnO3 using a self-consistent ab-initio LCAO method. We employed a local density potential. The calculated electronic structure suggests that the material i s in a half-metallic state. The calculated average magnetic moment for the half-metallic phase is 3.75 mu(B) per Mn. This value is very close to the e xperimental values of 3.7 mu(B) per Mn. The real part of the optical conduc tivity, sigma(1)(omega), from the direct band transitions, is predicted. Th e calculated optical conductivity shows that for photon energies below 2.4 eV, the electronic states of minority spin do not contribute to the optical transitions.