Calibration of multi-layered probes with low/high magnetic moments

TL;DR

This paper introduces a comprehensive method for visualizing, quantifying, and calibrating multi-layered magnetic force microscopy probes with controllable high/low magnetic moments, combining experimental visualization, in situ studies, and numerical modeling.

Contribution

It presents a novel integrated approach for the calibration of complex magnetic probes with multiple stable magnetic states using visualization, in situ measurements, and numerical modeling.

Findings

Distinct stray field distributions for different magnetic states

Quantitative magnetic moment values obtained via RSTTF

Modeling confirms experimental measurements

Abstract

We present a comprehensive method for visualisation and quantification of the magnetic stray field of magnetic force microscopy (MFM) probes, applied to the particular case of custom-made multi-layered probes with controllable high/low magnetic moment states. The probes consist of two decoupled magnetic layers separated by a non-magnetic interlayer, which results in four stable magnetic states: +/-ferromagnetic (FM) and +/-antiferromagnetic (A-FM). Direct visualisation of the stray field surrounding the probe apex using electron holography convincingly demonstrates a striking difference in the spatial distribution and strength of the magnetic flux in FM and A-FM states. In situ MFM studies of reference samples are used to determine the probe switching fields and spatial resolution. Furthermore, quantitative values of the probe magnetic moments are obtained by determining their real space tip transfer function (RSTTF). We also map the local Hall voltage in graphene Hall nanosensors induced by the probes in different states. The measured transport properties of nanosensors and RSTTF outcomes are introduced as an input in a numerical model of Hall devices to verify the probe magnetic moments. The modelling results fully match the experimental measurements, outlining an all-inclusive method for the calibration of complex magnetic probes with a controllable low/high magnetic moment.