New characteristic parameter of energy loss in permalloy

Characteristic parameters of energy storage and loss in soft magnetic materials (SMMs), product S of initial susceptibility chi(i )and resonance frequency omega(r) and product L of maximum chi(m)" and half width Delta omega of imaginary part, were introduced in permalloy films. Expressions of characteristic parameters were derived from Landau-Lifshits-Gilbert equation with a general anisotropic free energy model. It was found S = L equals to intrinsic quantity of SMMs Q = gamma M-s root 1+H-perpendicular to/H-|| , where gamma is the gyromagnetic ratio, is the saturation magnetization, and H-perpendicular to and H-|| are mutually orthogonal effective magnetic fields. In the presence of eddy current, it was found M-S remains equal to Q while L < Q results from inhomogeneity of microwave magnetic field caused by eddy current. Moreover, a linear scale of L/S versus Gilbert damping factor alpha was found in permalloy films with different thicknesses. Hence, our findings provide a new perspective on energy storage and loss of SMMs.