Control of transport phenomena in magnetic heterostructures by wavelength modulation

TL;DR

This paper shows how changing the wavelength of optical excitation can control energy flow in magnetic heterostructures, enabling new ways to manipulate ultrafast spintronic devices.

Contribution

It introduces an advanced wavelength-dependent μT-model for multilayer structures, predicting reversible energy flow in Ni/Au bilayers based on excitation wavelength.

Findings

Energy flow from Ni to Au can be reversed by wavelength change.

Simulation results match magneto-optical Kerr measurements.

Wavelength modulation offers control over energy transport in magnetic multilayers.

Abstract

We demonstrate the tuneablity of the ultrafast energy flow in magnetic/non-magnetic bilayer structures by changing the wavelength of the optical excitation. This is achieved by an advanced description of the temperature based $\mu$T-model that explicitly considers the wavelength- and layer-dependent absorption profile within multilayer structures. For the exemplary case of a Ni/Au bilayer, our simulations predict that the energy flow from Ni to Au is reversed when changing the wavelength of the excitation from the infrared to the ultraviolet spectral range. These predictions are fully supported by characteristic signatures in the magneto-optical Kerr traces of the Ni/Au model system. Our results will open up new avenues to steer and control the energy transport in designed magnetic multilayer for ultrafast spintronic applications.