Magnetic Irreversibility and Magnetocrystalline Anisotropy in Nanocrystalline Nickel

摘要

Magnetic properties of nanocrystalline Ni samples, with average grain sizes, d = 11(1) nm, 19(1) nm and 30(2) nm, synthesized by pulse electrodeposition, have been studied. We observed that (i) at low temperatures, the effective magneto-crystalline anisotropy constant, K_1, increases with the crystallite size so as to reach the bulk value at d = 30 nm, and (ii) the rate of thermal decline of K_1(T) slows down as the crystallite size reduces.