Resonant inter-mode second harmonic generation by backward spin waves in YIG nano-waveguides

TL;DR

This paper demonstrates highly efficient resonant second harmonic generation by backward volume spin waves in YIG nano-waveguides, operating at microwave powers around 10^-4 W and at zero bias magnetic field, with waves propagating in opposite directions.

Contribution

It experimentally shows a novel inter-mode second harmonic generation mechanism using backward spin waves in nanoscale YIG waveguides, enabling zero-field operation.

Findings

Resonant second harmonic generation achieved at microwave powers of ~10^-4 W.

Backward waves generate second harmonics propagating opposite to initial waves.

Process occurs at zero bias magnetic field.

Abstract

We experimentally study nonlinear generation of the second harmonic by backward volume spin waves propagating in microscopic magnonic waveguides fabricated from a low-loss magnetic insulator with a thickness of several tens of nanometers. We show that highly efficient resonant second harmonic generation is possible in the inter-mode regime at microwave powers of the order of 10^-4 W. In contrast to previously observed second harmonic generation processes, the generation by backward waves is characterized by the nonlinearly generated waves propagating opposite to the initial waves, and can be realized at zero bias magnetic field.