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Mutual phase-locking of microwave spin torque nano-oscillators



Shehzaad F. Kaka, Matthew Pufall, William Rippard, Thomas J. Silva, Stephen E. Russek, Jordan A. Katine


The spin torque effect that occurs in nanometre-scale magnetic multilayer devices can be used to generate steady- state microwave signals in response to a d.c. electrical current. This establishes a new functionality for magneto-electronic structures that are more commonly used as magnetic field sensors and magnetic memory elements. The power emitted from a single spin torque nano-oscillator (STNO) is at present typically less than 1 nW. To achieve a more useful power level (on the order of microwatts), a device could consist of an array of phase coherent STNOs, in a manner analogous to arrays of Josephson junctions and large semiconductor oscillators. Here we show that two STNOs in close proximity mutually phase-locklong dash)that is, they synchronize, which is a general tendency of interacting nonlinear oscillator systems. The phase-locked state is distinct, characterized by a sudden narrowing of signal linewidth and an increase in power due to the coherence of the individual oscillators. Arrays of phase-locked STNOs could be used as nanometre-scale reference oscillators. Furthermore, phase control of array elements (phased array) could lead to nanometre-scale directional transmitters and recievers for wireless communications.


microwave nano-oscillators, nano-magnetic devices, Spin torque, spintronics


Kaka, S. , Pufall, M. , Rippard, W. , Silva, T. , Russek, S. and Katine, J. (2005), Mutual phase-locking of microwave spin torque nano-oscillators, Nature, [online], (Accessed July 16, 2024)


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Created September 14, 2005, Updated October 12, 2021