High Spin Polarization of Charge Carriers in Half-metallic-ferrimagnetic Double Perovskites Sr2CoPtO6 and Sr2NiPtO6 at Room Temperature

Abstract

In the search for new half-metallic spintronics materials, with high spin polarization at room temperature, we have studied novel platinum double perovskite oxides Sr2CoPtO6 and Sr2NiPtO6. The structural, electronic, magnetic properties have been studied by using the self-consistent full-potential linear muffin-tin orbital (FP-LMTO) ab-initio method. Calculations are performed by mean of the localspin-density approximation plus Hubbard parameter (LSDA+U) method. Our results of density of states predict a half-metallic ferrimagnetic (HM-FiM) character with total spin magnetic moments of 3.5 μB and 3.0 μB per unit cell for Sr2CoPtO6 and Sr2NiPtO6, respectively. It is established that the FiM character is attributed to both the superexchange (SE) mechanism and localized double exchange (DE) mechanism via the pdd-π Co/Ni (eg) – O – (2pπ) – Pt (eg) coupling and the latter is also believed to be the origin of the high spin polarization of Sr2CoPtO6 and Sr2NiPtO6.