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Title Observation of linear spin wave dispersion in the reentrant spin glass Fe sub 0 sub . sub 7 Al sub 0 sub . sub 3
Author(s) Shapiro, S M ; Bao, W ; Raymond, S ; Lee, S H ; Motoya, K
In: Appl. Phys. A 74 , 1 (2002) s859-s861
Subject category Condensed Matter
Abstract Fe sub 0 sub . sub 7 Al sub 0 sub . sub 3 is a reentrant spin glass, which undergoes a transition from a paramagnet to a disordered ferromagnet at T sub c propor to 500 K; at a lower temperature the spins progressively freeze and it exhibits a spin-glass-like behavior. In the ferromagnetic phase spin waves with a q sup 2 dispersion are observed at small q, which broaden rapidly and become diffusive beyond a critical wave vector q sub 0. On cooling the spin waves also disappear and a strong elastic central peak develops. For measurements around the (1,1,1) Bragg peak, a new sharp excitation is observed which has a linear dispersion behavior. It disappears above T sub c , but persists throughout the spin-glass phase. It is not present in the stoichiometric Fe sub 3 Al material. (orig.)

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