Spin correlation and slow dynamics in concentrated spin-glasses

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Although the problem of slow dynamics is a central issue of spin-glass, experimental studies have been limited to macroscopic measurements, such as the time evolution of thermo-remnant magnetization. In previous neutron scattering studies we showed that magnetic clusters play an important role for the reentrant spin-glass transition, and that a wide variety of spin dynamics observed by inelastic neutron scattering studies can be attributed to differences in the size and number of the magnetic clusters. Based on these studies, we speculate that the mechanism of slow dynamics might most directly be probed by an observation of the time evolution of the magnetic diffuse scattering arising from magnetic clusters.In this work, we made a time-resolved small-angle neutron scattering experiment on two kinds of concentrated spin glass alloys FeィイD265ィエD2(NiィイD21-xィエD2MnィイD2xィエD2)ィイD235ィエD2 and CuィイD22ィエD2)MnィイD21-xィエD2TiィイD2xィエD2)Al.The time variation of the magnetic diffuse scattering intensity after being quenched into the RSG phase was detected up to 20 hours. The observation showed that the sensitivity of the present experimental method satisfies the condition to detect the slow dynamics. A quantitative analysis together with an improvement of the counting statistics by repetition of same heat cycles is under way.