Ab-initio study of anisotropy and nonuniaxial anisotropy coefficients in Pd nanochains

Orbital moments and magnetocrystalline anisotropies of linear chains, ladder and zigzag belts of Pd are investigated by first-principle calculations. The second- and fourth-order anisotropy coefficients have been determined, and there are generally strong nonuniaxial contributions, yielding a saddle point in the energy landscape of the zigzag nanobelt. For some directions, spin (S) and orbital moment (L) are strongly noncollinear. In the ladder and zigzag belts, the maximum angle between spin and orbital moment is about 23°, but for the monatomic chain, we find an unexpected continuous change in the angle, covering the whole range between 0° and 180°.