Study of the sign change of exchange bias across the spin reorientation transition in Co(Cr 1− x Fe x ) 2 O 4 ( x = 0.00–0.125)

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We present the evolution of novel phenomena of magnetic compensation effect, exchange bias (EB) effect and the field induced anomalies in ‘ F e ’ substituted multiferroic compound C o C r 2 O 4 . A few percent of ‘ F e ’ substitution for ‘ C r ’ in C o C r 2 O 4 results in the reversal of field cooled magnetization under low applied fields below compensation temperature T comp . Further, increase in the field leads to the spin reorientation transition ( T SR ). Signature of EB in a narrow temperature window in the vicinity of T SR and its sign change across T SR is observed. Magnitude of EB depends on the amount of compensation and rigidity of the spin reorientation. We also notice the appearance of positive EB below the lock-in transition ( T L ). Presence of unidirectional anisotropy developed in the commensurate spin-spiral below T L could be responsible for the appearance of EB below T L .