Half-point fields for microwave magnetoabsorption in colossal magnetoresistance manganite powders

We reexamine the recently discovered giant microwave magnetoimpedance in manganite powders. The absorption consists of two components, a resistive part which is only weakly field dependent, and a low-temperature spin-dependent part, which gives rise to the giant effects. We propose that the half-point field H₀, required to reduce the spin-dependent absorption to one half of its value at zero field, arises from the magnetic anisotropy consequent on the strains in the grains.