Deeply nonlinear excitation of self-normalised exchange spin waves

TL;DR

This paper demonstrates a novel nonlinear excitation method for exchange spin waves in nanoscale waveguides, achieving high efficiency and amplitude stability, which advances wave-based computing technologies.

Contribution

It introduces a deeply nonlinear excitation mechanism for exchange spin waves with self-normalized amplitudes, enabling robust and efficient on-chip magnonic circuits.

Findings

Achieved a nonlinear frequency shift >2 GHz

Excited exchange spin waves with wavelengths down to 10 nm

Attained excitation efficiency >80% with amplitude independence from input power

Abstract

Spin waves are ideal candidates for wave-based computing, but the construction of magnetic circuits is blocked by a lack of an efficient mechanism to excite long-running exchange spin waves with normalised amplitudes. Here, we solve the challenge by exploiting the deeply nonlinear phenomena of forward-volume spin waves in 200 nm wide nanoscale waveguides and validate our concept with microfocused Brillouin light scattering spectroscopy. An unprecedented nonlinear frequency shift of >2 GHz is achieved, corresponding to a magnetisation precession angle of 55{\deg} and enabling the excitation of exchange spin waves with a wavelength of down to ten nanometres with an efficiency of >80%. The amplitude of the excited spin waves is constant and independent of the input microwave power due to the self-locking nonlinear shift, enabling robust adjustment of the spin wave amplitudes in future on-chip magnonic integrated circuits.