An ab initio study of the magnetocrystalline anisotropy and magnetoelastic coupling of half-metallic CrO2

Abstract First-principles density functional calculations of the total energy, magnetic moments and magnetocrystalline anisotropy energy (MAE) of CrO 2 as a function of both volume and uniaxial strain along the c -axis have been performed. The highly accurate all-electron full-potential linearized augmented plane wave method and the generalized gradient approximation to the exchange–correlation potential are used. The calculated structural properties (lattice constants and unit cell volume) are in excellent agreement with experiments (with 0.5%). The calculated bulk and Young’s modulii are 2.56 and 2.02 Mbar, respectively. The calculated MAE increases almost linearly with the uniaxial strain and remains positive in the strain range of −4–4%. Thus, the calculations predict that the easy magnetization axis is along the c -axis, in agreement with experiments. However, the calculated anisotropy constant is about six times larger than the measured value. The calculated magnetoelastic coupling constant is 1.2×10 7 erg/cm 3 and the magnetostriction coefficient λ 001 is −2.59×10 −5 .