Spin valve structures with double exchange biased fields

Abstract

We have proposed a new type of double exchange-biased Cu/FeMn/NiFe/Cu/NiFe/FeMn/Ta spin valve with two ferromagnetic layers exchange biased in opposite directions by two antiferromagnetic layers. Sputtering the bottom and top NiFe/FeMn bilayer in magnetic fields of opposite directions, the hysteresis loop, which consists of two loops shifted in opposite directions from the zero magnetic field, was obtained. The NiFe layers are in the antiparallel state in zero magnetic field, and the switching to parallel state can be tuned by selecting the proper exchange bias fields. Moreover, due to the modified spin valve expanding the switching window of the antiparallel state, it makes fabricating the spin valve more flexible, especially for spin valves in which enough large exchange coupling cannot be realized at some fabricating conditions.