Tunneling magnetoresistance effect of granular Co-Ta-O films sputtered under an oblique cathode arrangement

Tunneling magnetoresistance of granular Co-Ta-O films sputtered under an obliquely arranged electrodes was investigated as a function of the film thickness and the concentration of Co to Ta₂O₅ . Formation of micro-scale structures such as corrugated surface elongating perpendicular to the incident ion-beam (thickness <50 nm) and columnar structure inclined to the normal of the film plane (thickness >50 nm) were quite similar to vacuum evaporated films, As a result of these structures, the resistivity at zero field ρ(0) and the resistivity change with field Δρ became about 1 order of magnitude larger compared to those of films sputtered under ordinary parallel electrode arrangement