Anisotropic magnetoresistance with cubic anisotropy and weak ferromagnetism: A new paradigm

Earlier atomic d-state models of anisotropic magnetoresistance {Δ}{ρ}/{ρ} are reviewed and found to suffer from a weak-ferromagnetism ``catastrophe:'' a nonphysical finite value of {Δ}{ρ}/{ρ} as exchange splitting goes to zero. New calculations of {Δ}{ρ}/{ρ}, including cubic anisotropy, avoid this problem and offer a new paradigm for interpreting experiments on systems with various band structures: dilute polycrystalline nickel alloys with virtual-bound-state (VBS) and non-VBS impurities, and also weak concentrated ferromagnets like Fe-Ni Invar. p states are also found to give nonzero {Δ}{ρ}/{ρ} in an atomic model.