Selective and Fast Plasmon-Assisted Photo-Heating of Nanomagnets; A New Route for Opto-Activated Nanomagnetic Logic and Artificial Spin Systems

TL;DR

This paper demonstrates a contactless, rapid, and spatially selective method for controlling the temperature of nanomagnets using plasmon-assisted photo-heating, enabling advanced applications in nanomagnetic logic and artificial spin systems.

Contribution

It introduces a novel hybrid plasmonic nanoheater approach for fast, localized, and polarization-dependent thermal control of nanomagnets, surpassing traditional thermal methods.

Findings

Achieved temperature increases of several hundred Kelvins in nanomagnets.

Demonstrated sub-nanosecond, sublattice-specific heating using polarization control.

Reduced magnetic coercive fields through thermally-activated moment reversals.

Abstract

Thermal relaxation of nanoscale magnetic islands, mimicking Ising macrospins, is indispensable for studies of geometrically frustrated artificial spin systems and low-energy nanomagnetic computation. Currently-used heating schemes based on contact to a thermal reservoir, however, lack the speed and spatial selectivity required for the implementation in technological applications. Applying a hybrid approach by combining a plasmonic nanoheater with a magnetic element, in this work we establish the robust and reliable control of local temperatures in nanomagnetic arrays by contactless optical means. Plasmon-assisted photo-heating allows for temperature increases of up to several hundred Kelvins, which lead to thermally-activated moment reversals and a pronounced reduction of the magnetic coercive field. Furthermore, the polarization-dependent absorption cross section of elongated plasmonic elements enables sublattice-specific heating on sub-nanosecond time scales. Using optical degrees of freedom, i.e. focal position, polarization, power, and pulse length, thermoplasmonic heating of nanomagnets offers itself for the use in flexible, fast, spatially-, and element-selective thermalization for functional magnetic metamaterials.