Metamagnetism and nanosize effects in the magnetic properties of the quasi-two-dimensional systemβ-Ni(OH)_2

摘要

Details of structural and magnetic properties of a sample of β-Ni(OH)_2 with nanoplate morphology (sample A) are compared with those of the hydrothermally synthesized bulklike β-Ni(OH)_2, sample B. Transmission electron microscopy, x-ray diffraction, infrared spectroscopy, and thermogravimetric analysis were used for structural characterization whereas studies of magnetic properties covered the temperature range of 2-350 K in magnetic fields upto H=180 kOe. Temperature dependence of the low-field susceptibilities, x(ZFC) and X(FC), showed that x(ZFC) peak at T_P=24.5 K (26.5 K) for sample A (B) with x(FC) > x(ZFC) below T_p. Curie-Weiss fit of x(ZFC) for T>T_P for sample A (B) yields 0=20.5 K (19.8 K) and magnetic moment fi = 2.92 μ_b (3.30 μB)/Ni~(2+). Measurements of the magnetization M vs H for T