Ferromagnetic Resonance in Nickel and Iron

Abstract

The ferromagnetic resonance linewidth has been measured at frequencies from 9–57 kMc/sec at room temperature in bulk single‐crystal samples of nickel and in thick single‐crystal whiskers of iron. The results for nickel can be accounted for by relaxation damping described by a frequency‐independent Landau‐Lifshitz coefficient λ=2.3×10⁸ sec⁻¹ plus a smaller contribution from the exchange‐conductivity mechanism. The widths in iron are found to vary as the square root of the frequency and are due mainly to exchange‐conductivity broadening. They can be fit with exchange stiffness 1.9×10⁻⁶ erg/cm (known from other experiments), magnetic surface‐anisotropy energy 0.4 erg/cm², and Landau‐Lifshitz relaxation parameter ≲0.7×10⁸ sec⁻¹.