DETERMINATION OF THE INTERNAL MAGNETIC-FIELD FROM THE A-T CRITICAL LINE IN MAGNETIC SEMICONDUCTOR THIN-FILMS

The de Almeida-Thouless (A-T) critical line for CdCr2-2xIn2xSe4 thin f ilms in the spin glass (SG) state was found from the irreversibilities between field cooled and zero-held cooled DC magnetization. The SG st ate consists of an infinite ferromagnetic network (IFN) with long-rang e ferromagnetic order and finite spin clusters (FSC) randomly distribu ted in the IFN. The A-T line is described by the relation tau similar to (h(eff))(2/3) for the normalized effective field h(eff) = h(a) + h( m). The first term stands for the external magnetic held while the sec ond one is related to the internal field of the IFN. The value of h(m) was found to depend on the indium concentration. (C) 1998 Elsevier Sc ience B.V. All rights reserved.