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Publication Citation: Mutual phase-locking of microwave spin torque nano-oscillators

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Author(s): Shehzaad F. Kaka; Matthew R. Pufall; William H. Rippard; Thomas J. Silva; Stephen E. Russek; Jordan A. Katine;
Title: Mutual phase-locking of microwave spin torque nano-oscillators
Published: September 15, 2005
Abstract: 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-lock{long 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.
Citation: Nature
Volume: 437
Pages: pp. 389 - 392
Keywords: microwave nano-oscillators,nano-magnetic devices,Spin torque,spintronics
Research Areas: Electromagnetics
PDF version: PDF Document Click here to retrieve PDF version of paper (399KB)