Long-Time Variation of Magnetization in Concentrated Spin-Glasses

Abstract

Time variations of magnetization MðtÞ in reentrant spin-glass (RSG) alloys Fe 65 (Ni 0:866 Mn 0:134 ) 35 , Fe 65 (Ni 0:60 Mn 0:40 ) 35 and Fe 0:70 Al 0:30 , together with a typical spin-glass alloy Cu 0:95 Mn 0:05 , have been measured under various combinations of temperature (T), magnetic field (H) and waiting time (t w ). The observed MðtÞ for all samples under various combinations of T, H and t w can be traced by a newly proposed function within the time range 12 < t < 10 5 s. The time variation behavior for each measurement is well represented by a characteristic time t max which corresponds to the maximum position of the relaxation rate SðtÞ. The characteristics of long-time variation of MðtÞ in the RSG materials have been discussed based on a magnetic cluster model.

Contrasting the magnetic response between a magnetic glass and a reentrant spin glass

“…2 We shall now discuss the characteristic metastable behaviour associated with the RSG and MG state. The metastable response of SG and RSG systems continues to remain a subject of active interest 23 . The ZFC state of these systems show strong relaxation in magnetization, while the field cooled state does not 12,13 .…”