Coercivity and exchange bias of Mn_(0.25)Ti_(1.1)S_2 in the cluster-glass state

摘要

Magnetic measurements have been carried out on the Mn-intercalated transition-metal dichalcogenide Mn_(0.25)Ti_(1+y)S_2. The material, which contained a concentration y≈0.1 of excess intercalated Ti, exhibited paramagnetic behavior at high temperatures with an effective moment per Mn ion of μeff=6.01 ±0.23 μB, which shows that the system comprises localized Mn~(2+) moments. A Curie-Weiss temperature Θcw= -26 ± 1 K indicated that antiferromagnetic interactions were dominant. Deviation from Curie-Weiss behavior below 100 K signaled the formation of antiferromagnetically correlated clusters. Bifurcation of the zero-field-cooled and field-cooled magnetizations below 20 K indicated a transition to a cluster-glass state. The cluster-glass state exhibited hysteresis and a loop shift indicating exchange bias. The behavior of the coercivity and exchange bias can be understood using a model in which frozen spins at the periphery of a cluster interact with the antiferromagnetically correlated interior.