Static and dynamic properties of the (FexCr1-x)75P15C10 reentrant-spin-glass amorphous alloy.

Abstract

The reentrant-spin-glass behavior for members of the amorphous (${\mathrm{Fe}}_{\mathit{x}}$${\mathrm{Cr}}_{1\mathit{\ensuremath{-}}\mathit{x}}$${)}_{75}$${\mathrm{P}}_{15}$${\mathrm{C}}_{10}$ and crystalline ${\mathrm{Fe}}_{\mathrm{x}}$${\mathrm{Cr}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$ systems are found to be similar when the ${T}_{C}$'s are the same. This suggests some relationship between the width of the exchange distribution and the average exchange. We have constructed a phase diagram for these systems by combining M\"ossbauer, magnetization, and neutron scattering techniques. The ferromagnetic transitions appear conventional in all of these techniques. We assign three characteristic temperatures to the reentrant-spin-glass behavior. The highest temperature, ${T}^{\mathrm{*}}$, corresponds to the first appearance of anomalies in the spin-wave dynamics and may also be related to the canting transition. The middle temperature, ${T}_{1}$, indicates the maximum in the zero-field-cooled magnetization, and also the approximate first appearance of anomalous small-angle neutron scattering. The magnetic structural changes are most pronounced below the lowest characteristic temperature, ${T}_{2}$, where strong irreversibilities occur in the magnetization and the small-angle neutron scattering becomes sufficiently intense that the correlation length appears to decrease. We make a rough correspondence with the phase diagram proposed by Gabay and Toulouse.