Magnetic properties of 2D Ising mesoscopic ferromagnet Ni(OH)2 monolayer nanoclusters

Ni(OH)(2) monolayer nanoclusters (Ni-MNC) in amorphous SiO2 were prepared by the wet method by mixing of NiCl2.6H(2)O and Na2SiO3.9H(2)0 aqueous solutions. The AC magnetic susceptibilities of Ni-MNC in a-SiO2 were measured between 4 K and 40 K from 98 Hz to 8 kHz by Hartshorn bridge method, By the Cole-Cole plots for AC chi' and chi", the static chi, averaged relaxation time tau(AV) was estimated. The magnetic viscosity S, derived from time decay of field cooled magnetization M-FC, showed similar behavior with 1/tau(AV). The close value of ferromagnetic transition temperature T-C and quantum mesoscopic tunneling temperature T-Q might mean the characteristic of 2D Ising ferromagnetic mesoscopic system. (C) 1998 Elsevier Science B.V. All rights reserved.