Spin-wave-beam driven synchronization of nanocontact spin-torque oscillators

Abstract

The synchronization of multiple nanocontact spin-torque oscillators (NC-STOs) is mediated by propagating spin waves (SWs). Although it has been shown that the Oersted field generated in the vicinity of the NC can dramatically alter the emission pattern of SWs, its role in the synchronization behaviour of multiple NCs has not been considered so far. Here we investigate the synchronization behaviour in multiple NC-STOs oriented either vertically or horizontally, with respect to the in-plane component of the external field. Synchronization is promoted (impeded) by the Oersted field landscape when the NCs are oriented vertically (horizontally) due to the highly anisotropic SW propagation. Not only is robust synchronization between two oscillators observed for separations larger than 1,000 nm, but synchronization of up to five oscillators, a new record, has been observed in the vertical array geometry. Furthermore, the synchronization can no longer be considered mutual in nature.

Enhancing the injection locking range of spin torque oscillators through mutual coupling

“…In the last few years, many efforts have been made to improve the spectral purity of spintorque oscillators, a crucial step towards most applications. From these studies, a promising approach consists in the synchronization of the oscillators to an external microwave source [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] (injection locking), or to other oscillators [21][22][23][24][25][26][27] (mutual synchronization). In both cases, a crucial parameter to optimize for applications is the locking range, which should be as large as possible.…”

Phase-locking of multiple magnetic droplets by a microwave magnetic field

“…One promising approach to increasing the output power has been suggested by using the phase-locking mode of an array of STOs through the synchronization technique. 3,[19][20][21][22][23][24][25][26][27][28] This is a very challenging issue for the droplet-based NC-STOs due to the strongly non-linear soliton property of the magnetic droplets. To gain insight into the nature of droplet dynamics, micromagnetic simulations have been powerful tools.…”

Time-domain stability of parametric synchronization in a spin-torque nano-oscillator based on a magnetic tunnel junction

“…However, practical applications of these devices are hindered by a large linewidth due to high phase noise and by a low output power. A solution to these limitations is the synchronization of multiple oscillators [20][21][22][23][24][25][26].…”