CALCULATION OF THE MAGNETOCRYSTALLINE ANISOTROPY ENERGY USING A TORQUE METHOD

We calculate the torque on a magnetic moment with arbitrary orientatio n in a solid and use it to calculate the magnetocrystalline anisotropy energy (MAE) of bulk materials by integrating the torque along an ang ular path connecting the easy and hard magnetization directions. We ap ply this approach to the calculation of the MAE of elemental ferromagn ets Ni and Fe using a tight-binding model with an added spin-orbit-cou pling (SOC) term lambda(SO)L . S. The MAE for both Fe and Ni is comput ed for a wide range of values of the SOC strength. Our results for the MAE calculated with the torque method agree with the MAE determined f rom energy differences. The convergence rate as a function of k-vector needed for integrating over the Brillouin zone for the torque method is comparable to the convergence rate of conventional energy differenc e schemes. We compare the calculated torque as function of angle to th e lowest order term in the expansion in anisotropy constants. (C) 1997 American Institute of Physics.