Nano-oxide layer formed on ruthenium of synthetic pinned-structure spin valve by ion beam and cluster ion beam oxidation

In this paper, we report the performance of bottom synthetic spin-valve films with a newly developed ruthenium (Ru)-based nano-oxide layer (NOL). Two energetic oxidation techniques using an ion beam and a gas cluster ion beam were applied for the formation of the Ru NOL in the synthetic pinned layer. The giant magnetoresistance (GMR) was greatly enhanced from 13.8% to 15.7% with no sign of degradation in the pinning strength. In addition, these Ru NOL-bearing spin-valve films have demonstrated an excellent thermal stability, withstanding repeated thermal annealing cycles at elevated temperatures. This performance is clearly superior to that from the spin-valve films with a conventional CoFe-based NOL. The Ru NOL has shown a great potential for high-amplitude read sensor applications.