Long magnetic relaxation time of Fe-Bi spin-glass system

Bi and Fe are mutually insoluble either in the solid or liquid states. Howe ver. metastable Fe-Bi alloys can be made using the rapidly quenching method . We have successfully prepared metastable FexBi1-x alloys over a wide comp osition range by DC magnetron co-sputtering. The X-ray diffraction results indicate that the magnetic Fe atoms are gradually replacing the Bi atoms in a rhombohedral structure for x < 0.6. The magnetic measurements show that a spin-glass results with the freezing temperature increasing with x. In ad dition. a long relaxation characteristic time tau is observed which is abou t 20 h at room temperature. The slow relaxation behavior of the Fe-Bi syste m can be qualitatively explained from the picture that Bi has a large spin- orbit splitting. (C) 2001 Elsevier Science B.V. All rights reserved.