US Patent 7589600 Spin oscillator device

A spin oscillator device generates a microwave output in response to an applied DC current. The device includes a spin momentum transfer (SMT) stack including a top electrode, a free layer, a nonmagnetic layer, a pinned magnetic structure, and a bottom electrode. A local magnetic field source adjacent the SMT stack applies a local magnetic field to the free layer to cause the magnetization direction of the free layer to be oriented at a tilt angle with respect to plane of the free layer. The local magnetic field source can include coils or an electromagnet structure, or permanent magnets in close proximity to the SMT stack.