Spin-valves with antiferromagnetic /spl alpha/-Fe/sub 2/O/sub 3/ layers

We report that the spin-valve films using the antiferromagnetic /spl alpha/-Fe/sub 2/O/sub 3/ layers show good MR response due to the coercivity difference in an as-deposited state and due to the unidirectional biasing field after magnetic annealing. Both the high coercivity and the biasing field of the pinned layer is caused by an exchange coupling. The obtained MR ratio of 6.1% is higher than those of the other spin-valves using Fe-Mn or Ni-Mn owing to the high resistivity of the /spl alpha/-Fe/sub 2/O/sub 3/. Further higher MR ratio of 10% is achieved by imposing 1 nm-thick Co layers at the Ni-Fe/Cu interfaces. It was found that the free layer coercivity of these spin-valves is smaller than that in the Co-Pt/Cu/Ni-Fe sandwiches having the similar high coercivity of the pinned layer. High thermal stability and corrosion resistance were also confirmed in the /spl alpha/-Fe/sub 2/O/sub 3/ spin-valves.