Polarization-analysis study of the atomic and spin-pair correlations in Ni0.76Mn0.24.

Abstract

Neutron diffuse scattering measurements were made on single-crystal Ni/sub 0.76/Mn/sub 0.24/ to determine the atomic and spin-pair correlations in the reentrant spin-glass state. The nuclear and magnetic diffuse scattering were separated by polarization analysis at T = 10 K in a field of 8.1 kOe applied parallel to Q. The nuclear cross section shows diffuse peaks at (100) and (110) due to atomic short-range order (ASRO) with a range of about 3a/sub 0/. The ASRO parameters for this quenched alloy were determined to 16 shells; these show a preference for like even-shell and unlike odd-shell neighbors. In the experimental geometry, the magnetic cross section determines the correlations between spin components transverse to the applied field, or magnetization direction. The magnetic short-range-order parameters alternate in sign for the first four shells and then remain positive at larger distances. This unusual result corresponds to the coexistence of short-range antiferromagnetic order with both short- and long-range ferromagnetic order.