Non-Adlerian synchronization of dipolar coupled vortex Spin-Torque Nano-Oscillators

TL;DR

This paper explores the complex synchronization behavior of dipolarly coupled vortex Spin-Torque Nano-Oscillators with varying pillar sizes, revealing a transition from Adlerian to non-Adlerian dynamics as size mismatch increases.

Contribution

It provides analytical and numerical insights into the synchronization transition of vortex STNOs with different diameters, highlighting the limits of Adler equation applicability.

Findings

Synchronization depends on interpillar distance and diameter mismatch.

Transition from Adlerian to non-Adlerian dynamics with increasing size difference.

Phase diagram illustrating synchronized and unsynchronized regimes.

Abstract

We investigate analytically and numerically the synchronization dynamics of dipolarly coupled vortex based Spin-Torque Nano Oscillators (STNO) with different pillar diameters. We identify the critical interpillar distances on which synchronization occurs as a function of their diameter mismatch. We obtain numerically a phase diagram showing the transition between unsynchronized and synchronized states and compare it to analytical predictions we make using Thiele approach. Our study demonstrates that for relatively small diameters differences the synchronization dynamics can be described qualitatively using Adler equation. However when the diameters difference increases significantly, the system becomes strongly non-Adlerian.