Magnetic anisotropy of Ni nano-crystals prepared with Gas-deposition method

Ni nano-crystals were prepared with Gas-deposition method. As deposited fil ms were composed of fine particles with approximately 10 nln in diameter. T hermal annealing was applied to increase the grain size. Coercive forces of the nano-crystals vary in accordance with the 6 powers of grain size. This is explained by the Random Anisotropy Model. Effective local magnetic anis otropy is deduced to be 1.9 similar to3.5 X 10(4) J/m(3) and the magnitude is 2 similar to5 times larger than that of bulk Ni. From the field cool mag netization measurement, He shift due to exchange anisotropy was not observe d. The oxygen atoms in nano-crystals are not responsible for the global ani sotropy but may reduce the exchange stiffness. (C) 2001 Acta Materialia Inc . Published by Elsevier Science Ltd. All rights reserved.