Low-temperature anomalous magnetic behavior of Co2TiO4 and Co2SnO4

We report the low-temperature anomalous magnetic behavior offerrimagnetic spinels cobalt orthotitanate (Co2TiO4), which exhibits magnetic compensation behavior across 31.74  K, and cobalt orthostannate (Co2SnO4) exhibiting two sequential magnetictransitions, namely (i)ferrimagnetic to paramagnetictransition with N éel temperature TN ∼ 41 K and reentrantspin-glass behavior with glasstransition temperature TSG ∼ 39 K. The Arrott plot (H/M versus M2) criterion has been used to extricate the order of sequential magnetictransitions occurring below TN. Negative slopes of the Arrott plots below 32  K, metamagnetic-like character of the M-H isotherms, anomalies in the specific-heat (CP T−1 versus T) below 15  K, and a zero-crossover of isothermal magnetic-entropy-change (ΔS) signify the presence of pseudo first-order discontinuous magnetic phasetransition in the low-temperature regime 5  K ≤ T ≤ 32 K. The dc- and ac-susceptibilities of both Co2TiO4 and Co2SnO4 are interpreted in terms of frozen-spin-clusters, which are responsible for very large magnitudes of thecoercivity HC ∼ 20 kOe and bipolar-exchange bias HEB ∼ −20 kOe observed below 10 K.

Source: Journal of Applied Physics - October 27, 2016 Category: Physics Authors: S. Nayak, K. Dasari, D. C. Joshi, P. Pramanik, R. Palai, A. Waske, R. N. Chauhan, N. Tiwari, T. Sarkar and S. Thota Source Type: research