Frequency dependent magnetic susceptibility of Ni(OH)2 monolayer nanoclusters

The a.c. magnetic susceptibility χac was measured for Ni(OH)2 monolayer nanoclusters (Ni-MNC) in the temperature region 4.2–20 K. The frequency dependence of χac was investigated between 98 Hz and 8 kHz with an a.c. field amplitude of 1.8 Oe. The magnetic freezing temperature T′f was measured above 10 K using the real and imaginary parts of χac, (χ′0, χ′ʹ0). The value of dynamic critical exponent zv was determined by applying a dynamic scaling law to the present results. It is considered that the finite two-dimensional ferromagnetic system of Ni-MNCs has magnetic order at 9.5 K, at which the non-linear a.c. magnetic susceptibility χ′2 has an anomalous dip.