Near-field magneto-caloritronic nanoscopy on ferromagnetic nanostructures

TL;DR

This paper introduces a novel near-field magneto-caloritronic imaging technique that maps local magnetization states of ferromagnetic nanostructures by detecting their thermal and magnetic responses to infrared excitation.

Contribution

It presents a new contrast mechanism for near-field optical microscopy based on magneto-caloritronic effects in magnetic nanostructures, supported by experimental and numerical analysis.

Findings

Demonstrated magnetic contrast via near-field thermal excitation

Estimated field enhancement and temperature profiles on nanostructures

Validated the approach with numerical simulations

Abstract

Near-field optical microscopy by means of infrared photocurrent mapping has rapidly developed in recent years. In this letter we introduce a near-field induced contrast mechanism arising when a conducting surface, exhibiting a magnetic moment, is exposed to a nanoscale heat source. The magneto-caloritronic response of the sample to near-field excitation of a localized thermal gradient leads to a contrast determined by the local state of magnetization. By comparing the measured electric response of a magnetic reference sample with numerical simulations we derive an estimate of the field enhancement and the corresponding temperature profile induced on the sample surface.