Realization of two-dimensional ferromagnetism with giant coercivity in ultrathinβ−Ni(OH)2layers grown on aMoS2surface

Abstract

Due to the charge transfer effect at the contact of transition metal (TM) and $\mathrm{Mo}{\mathrm{S}}_{2}$, the use of ferromagnets in $\mathrm{Mo}{\mathrm{S}}_{2}$ based spin transistor is not suitable. On the other hand, $\ensuremath{\beta}\text{\ensuremath{-}}\mathrm{Ni}{(\mathrm{OH})}_{2}$ is known to be a layered type material with antiparallel Ni spins in alternate layers. Here, an ultrathin layer of antiferromagnetic $\ensuremath{\beta}\text{\ensuremath{-}}\mathrm{Ni}{(\mathrm{OH})}_{2}$ is grown on the $\mathrm{Mo}{\mathrm{S}}_{2}$ surface to achieve complete ferromagnetism with giant coercivity (2925 Oe). The origin of this ferromagnetic ordering is the reduction of Ni spin moments in $\mathrm{Ni}{(\mathrm{OH})}_{2}$ layer adjacent to $\mathrm{Mo}{\mathrm{S}}_{2}$ surface due to charge transfer from S to Ni. The use of antiferromagnetic layered type material to achieve ferromagnetic ordering with giant coercivity is a new concept to realize perfect two-dimensional (2D) ferromagnets which have major advantages due to the huge change in coercivity with thickness.