On the nature of magnetic state in the spinel Co2SnO4

Abstract

In the spinel Co2SnO4, coexistence of ferrimagnetic ordering below TN ≃ 41 K followed by a spin glass state below TSG ≃ 39 K was proposed recently based on the temperature dependence of magnetization M(T) data. Here new measurements of the temperature dependence of the specific heat CP(T), ac-susceptibilities χ′(T) and χ″(T) measured at frequencies between 0.51 and 1.2 kHz, and the hysteresis loop parameters (coercivity HC(T) and remanence MR(T)) in two differently prepared samples of Co2SnO4 are reported. The presence of the Co2+ and Sn4+ states is confirmed by x-ray photoelectron spectroscopy (XPS) yielding the structure: Co2SnO4 = [Co2+][Co2+Sn4+]O4. The data of CP versus T shows only an inflection near 39 K characteristic of spin–glass ordering. The analysis of the frequency dependence of ac-magnetic susceptibility data near 39 K using the Vogel–Fulcher law and the power-law of the critical slowing-down suggests the presence of spin clusters in the system which is close to a spin–glass state. With a decrease in temperature below 39 K, the temperature dependence of the coercivity HC and remanence MR for the zero-field cooled samples show both HC and MR reaching their peak magnitudes near 25 K, then decreasing with decreasing T and becoming negligible below 15 K. The plot of CP/T versus T also yields a weak inflection near 15 K. This temperature dependence of HC and remanence MR is likely associated with the different magnitudes of the magnetic moments of Co2+ ions on the ‘A’ and ‘B’ sites and their different temperature dependence.