Spin Tunneling Junctions Using a Full Heusler Alloy

摘要

A spin valve type tunneling junction consisting of Co{sub}2Cr{sub}0.6Fe{sub}0.4Al (10nm)/AlO{sub}X (1.4nm) /CoFe (3nm) /NiFe (5nm) /IrMn (15nm) /Ta (5nm) was fabricated using metal masks, which was deposited on a thermally oxidized Si substrate without a buffer layer. The junction demonstrated large tunneling magnetoresistances of 16% at room temperature and 26.5% at 5K. The Co{sub}2Cr{sub}0.6Fe{sub}0.4Al Heusler alloy film exhibits the B2 structure, not the L2{sub}1 structure as expected in the bulk, but it has magnetic moment of 2.04μ{sub}B per formula unit at a low temperature, nearly the integer number of Bohr magnetons, suggesting a localized nature of ferromagnetism like many Heusler compounds, which is a necessary condition for half metallicity.