Unusual glassy states in LaMn0.5Fe0.5O3: Evidence of two distinct dynamical freezing processes

Abstract

An interesting scenario of unusual glassy states is observed from the dc and ac susceptibility measurements in LaMn0.5Fe0.5O3. The dc measurements at 5mT exhibit two distinct peaks at ∼20(Tg) and ∼255K(Tp). The large field-cooled effect and frequency-dependent results indicate a glassy state between Tg and Tp, while the relaxation dynamics does not show cooperative relaxation without aging, suggesting the existence of noninteracting clusters of frozen spin. On the other hand, the glassy state with clear evidence of a cooperative relaxation process is noticed below Tg, which has been characterized from the field- and frequency-dependent results associated with the evidence of aging. The nature of the cooperative glassy state does not meet the glassy features of classical spin-glass compounds.