Double perovskites such as Sr2FeMoO6 are materials with half-metallic ground states and ferrimagnetic Tc's well above room temperature. This paper is the second of our comprehensive theory for half-metallic double perovskites. Here we derive an effective Hamiltonian for the Fe core spins by "integrating out" the itinerant Mo electrons and obtain an unusual double-square-root form of the spin-spin interaction. We validate the classical spin Hamiltonian by comparing its results with those of the full quantum treatment presented in a companion paper. We then use the effective Hamiltonian to compute magnetic properties as a function of temperature and disorder and discuss the effect of excess Mo, excess Fe, and antisite disorder on the magnetization and Tc. We conclude with a proposal to increase Tc without sacrificing carrier polarization.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Apr 4 2013|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics