Mutual phase-locking of microwave spin torque nano-oscillators

Published

September 15, 2005

Author(s)

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

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-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.

Citation

Nature

Volume

437

Pub Type

Journals

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Keywords

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

Citation

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], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=31978 (Accessed October 8, 2025)