Asymptotic and leading "correction-to-scaling" susceptibility critical exponents and amplitudes for ferromagnets with quenched disorder

Abstract

Accurate values of the asymptotic susceptibility critical exponent (γ), critical amplitude (Γ), and the leading "correction-to-scaling" exponents and amplitudes for quench-disordered ferromagnets have been determined for the first time through an elaborate analysis of precise and comprehensive ac susceptibility data taken on amorphous Fe_xNi_80-xB₁₉Si₁(x =10, 13, and 16) alloys in the critical region. Consequently, the present work provides unambiguous experimental verification of theoretical predictions based on renormalization-group (RG) calculations, and testifies to their correctness by demonstrating that the exponent γ of the ordered three-dimensional Heisenberg ferromagnet is not affected by the presence of quenched disorder and that the "frozen" disorder plays the role of an irrelevant scaling field (in the RG sense).