Second anisotropy constant in cubic ferromagnetic crystals

Abstract

The second anisotropy constant, K2, is evaluated at 0°K for cubic, ferromagnetic crystals using two-particle dipole- and quadrupole-like interactions as perturbations on a molecular field Hamiltonian. In second- and third-order perturbation, the energy denominators are modified to take into account the effect on the molecular field of the exchange interaction of consecutively reversed spins. The expression for K2(0) is used in conjunction with that for K1(0) to calculate the values of the pseudodipolar and pseudoquadrupolar coupling constants for iron, cobalt, and nickel. For bcc Fe, DJ=0.0793 and QJ=0.00157, where JS=2.87×10-14 erg; for fcc Co, DJ=0.113 and QJ=0.000865, where JS=2.0×10-14 erg; and for fcc Ni, DJ=-0.0768 and Q=0, where JS=2.5×10-14 erg, although the application of the model to nickel is not entirely satisfactory. These values are used to predict the size of the third anisotropy constant and the paramagnetic resonance linewidth. © 1963 The American Physical Society.