Quantum spin tunneling of magnetization in small ferromagnetic particles

An approach is presented that can also account for the description of small ferromagnetic particle magnetization tunneling. An estimate of the saturation value of an external applied magnetic field along the easy axis is obtained. An analytic expression for the tunneling factor in the absence of an external magnetic field is deduced from the present approach that also allows one to obtain the crossover temperature characterizing the regime where tunneling is dominated by quantum effects. (C) 2009 Published by Elsevier B.V.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, CNPq, BrazilCAPES, BrazilCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo, FAPESP, BrazilFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP