Exchange interactions, spin waves, and Curie temperature inzincblende half-metallic sp-electron ferromagnets: the case of CaZ (Z = N, P, As, Sb)

Abstract

Using first-principle calculations in conjunction with the frozen-magnontechnique we have calculated the exchange interactions and spin-wavedispersions in the series of the zincblende half-metallic II–V (CaZ,Z = N, P, As, Sb) ferromagnets. The calculated exchange constants are used to estimate theCurie temperature within the random phase approximation. The large Stoner gap in thesealloys gives rise to well-defined undamped spin waves throughout the Brillouin zone.Moreover we show that the spin-wave stiffness constants for the considered systems areamong the largest available for local moment ferromagnets. The predicted Curietemperature of half-metallic CaN is noticeably higher than the room temperature withrespect to the other compounds, and thus we propose CaN as a promising candidate forfuture applications in spintronic devices.