Our recent paper about field-free spin torque oscillator using synthetic-ferromagnet is published on Physical Review B 87, 020409(R) (2013) (Rapid Communications).
In this paper, we predict that a ferromagneticaly coupled synthetic-ferromagnet (see the right figure) can be excited into dynamical precessional states by an applied current without external magnetic fields.
A spin-torque microwave oscillator is a device which can generate microwave frequency signals based on current-induced magnetization dynamics (using spin-transfer effect) and giant magneto-resistance (GMR) effect. Spin-torque oscillator is promising in wireless communications.
This work was carried out in collaboration with Dr. Yan Zhou and Prof. F. C. Zhang in The University of Hong Kong, and Prof. Gerrit Bauer in Tohoku University (as well as TU Delft).