Measurement of a Critical Exponent by a New Zero-Field Transmission Resonance Technique

The critical exponent β of Gd is measured directly for the first time by a new technique of ferromagnetic transmission resonance in zero external field. The technique consists of measuring the microwave power transmitted through a thin Gd film (47 μ) as a function of temperature. Analysis of the resulting line shape yields the value of conductivity σ=0.745×10¹⁶ sec^-1, spin relaxation time τ=7.3×10^-11 sec, Curie temperature TC=295^∘{}K, and critical exponent β=0.31±0.05.