Optothermal control of spin Hall nano-oscillators

TL;DR

This paper demonstrates optothermal tuning of spin Hall nano-oscillators using focused laser heating, enabling reversible control of their oscillation properties and significantly expanding their tunability.

Contribution

It introduces a method for optothermal control of SHNOs, showing reversible tuning of frequency and power, and highlights potential for optical manipulation in larger SHNO networks.

Findings

Laser tuning can shift frequency by up to 350 MHz.

Local temperature increase affects threshold current and signal jitter.

Optical control enables tuning without additional voltage gates.

Abstract

We investigate the impact of localized laser heating on the auto-oscillation properties of a 170 nm wide nano-constriction spin Hall nano-oscillators (SHNO) fabricated from a NiFe/Pt bilayer on a sapphire substrate. A 532 nm continuous wave laser is focused down to a spot size of about 500 nm at a power ranging from 0 to 12 mW. Through a comparison with resistive heating, we estimate a local temperature rise of about 8 K/mW. We demonstrate reversible laser tuning of the threshold current, the frequency, and the peak power, and find that the SHNO frequency can be tuned by up to 350 MHz, which is over three times more than the current tuning alone. Increasing the temperature also results in increased signal jitter, an increased threshold current, and a reduced maximum current for auto-oscillations. Our results open up for optical control of single SHNOs in larger SHNO networks without the need for additional voltage gates.