SPIN-DEPENDENT TUNNELING BETWEEN A SOFT FERROMAGNETIC LAYER AND HARD MAGNETIC NANOSIZE PARTICLES

Spin-dependent tunneling has been investigated for ferromagnetic tunne l junctions with a new structure, which consists of a hard ferromagnet ic insulating granular thin film sandwiched between two soft ferromagn etic layers; or soft ferromagnetic and non-ferromagnetic layers. The g ranular film, consisting of ferromagnetic Co80Pt20 nanosize particles embedded in a SiO2 matrix with 13 nm thickness, has a high coercive fo rce. The Blm was prepared by co-sputtering of Co80Pt20 and SiO2 target s on a glass substrate with a Cr or a Co80Pt20/Fe underlayer as a bott om electrode. A ferromagnetic Co9Fe layer as a top electrode was depos ited over the granular film to form cross pattern junctions of 0.01 mm (2) junction area through a metal mask. The tunneling magnetoresistanc e up to 4.5% at RT was observed for a Co9Fe/Co80Pt20-SiO2/Co80Pt20/Fe junction at a low field.