Crystal Field Analysis of the Magnetic Anisotropy of CeAgAs2

A. Elhag, K. Ayuel, A. Al-Qarni

Abstract: We have investigated the effect of crystal field potential together with the Ce - Ce exchange interaction on the magnetic anisotropy energy, magnetization, and magnetic susceptibility of the Kondo compound CeAgAs2. The effective Hamiltonian for the Ce3+ ion was approximated by assuming a tetragonal crystal field, for which the crystal field parameters are estimated using a maximally local-ized Wannier function approximation, while the exchange part is approximated by mean field approach. Energy eigenvalues and eigenvectors of the magnetic ion in the structure (Ce3+) are determined by diagonalizing the effective Hamiltonian and hence used to estimate the direction - dependent free energy. The magnetocrystalline anisotropy energy was extracted as well as magnetization and magnetic susceptibility in the principal crystallographic axes. Our results reveal that the c - axis is the hard direction of magnetiza-tion, while the ab plane is clearly the easy plane, in qualitative agreement with the experimental findings of previous investigations.

Keywords: Magnetocrystalline anisotropy, CeAgAs2, Crystal field. Mean field approximation