Transition from antiferromagnetic to ferromagnetic β-Co(OH)2 with higher Curie temperature

Abstract

β-Co(OH)2 intrinsically is an antiferromagnetic semiconductor with Néel temperature (TN) of ~ 11 K. On the other hand, a semiconducting ferromagnet is indeed a very important component and used as ferromagnetic contacts in spin transistors. Therefore, realization of a 2D ferromagnetic semiconductor with higher Curie temperature and coercivity is a genuine challenge. In earlier work, we have used interface interaction to achieve a transition from antiferromagnetic to ferromagnetic ordering when the antiferromagnetic Ni(OH)2, Co(OH)2 are grown on the MoS2 surface acting as a 2D template. Thus interface interaction largely depends on the thickness of both the magnetic material as well as the template material. The major limitation of the earlier work is that we could not reduce the thickness of the template (MoS2), because of the limitation in the synthesis condition. Therefore, in the present work, we have used WS2 as a 2D template, the thickness of which is reduced to about 3–4 layers. As a consequence, a large enhancement in Curie temperature (131 K), coercivity (1285 Oe) and magnetoresistance (46 %) are observed in the present sample of the ultrathin β-Co(OH)2 phase grown on a thin-layered WS2 sheet.