Atomic and magnetic short-range order in a Pt–8.8 at. % Mn spin-glass alloy

Abstract

The x-ray and neutron diffuse scattering intensities from a disordered Pt--8.8 at. % Mn spin-glass alloy were measured to obtain information about structural fluctuations due to atomic and magnetic short-range order. Diffuse maxima have been observed at the (100), (110) and their equivalent positions. Additional diffuse scatterings are also found at $(1/2,1/2,1/2)$ and its equivalent positions on the x-ray and neutron diffraction patterns at room temperature. Warren-Cowley atomic short-range order (ASRO) parameters were obtained by analyzing the x-ray diffuse intensity data. The correlation length has been deduced to be about $15\AA{}$ from estimating the reconstructed diffuse intensity distribution using the ASRO parameters determined experimentally. The neutron scattering result shows that a magnetic diffuse maximum appears at around $(1/2,0,0).$ The magnetic peak disappears at temperature far above the freezing temperature ${T}_{\mathrm{g}}$ at which a cusp-type peak is observed in the magnetic susceptibility measurement. The origin of the diffuse scattering is discussed in terms of a spin-density wave (SDW) induced by a Fermi surface nesting effect. The spin-glass-like behavior of Pt-Mn alloys is interpreted by the model of dynamically fluctuating SDW clusters as proposed for other metallic spin-glass alloys.