Inhomogeneous splitting of impurity-spin energy levels in mesoscopic wires

The Hamiltonian, which describes the surface-induced anisotropy for impurity spin in mesoscopic wires of dilute magnetic alloys, is derived for the wires with a rectangular cross-section and rough surfaces. We show that due to the combined effect of the four surfaces of the wire, the impurity-spin energy spectra are substantially different from those in a semi-infinite host. Moreover, we find that a moderate roughness of the surface enhances the splitting of the impurity-spin energy level.