Correlation induced half-metallicity in a ferromagnetic single-layered compound: Sr 2 CoO 4

摘要: The electronic and magnetic properties of ${\text{Sr}}_{2}{\text{CoO}}_{4}$ compound have been studied using ab initio electronic-structure calculations. As opposed to a generalized gradient approximation (GGA) calculation, which gives ferromagnetic metallic solution, $\text{GGA}+U$ calculations provide two kinds solutions: (i) half-metallic (ii) metallic. solution is ground state the system one metastable state. strong hybridization between $\text{Co}\text{ }3d$ $\text{O}\text{ }2p$ orbitals decides compound. total moment per formula unit found be $\ensuremath{\sim}3{\ensuremath{\mu}}_{B}$ $(S=3/2)$. Our give magnetocrystalline anisotropy energy $\ensuremath{\sim}2.7\text{ }\text{meV}$, provides good description experimentally observed large anisotropy. Heisenberg exchange parameters up fourth nearest neighbors are also calculated. mean-field theory ${T}_{C}=887\text{ }\text{K}$. possible physical implications discussed.