# Detection of nonmagnetic metal thin film using magnetic force microscopy

## TL;DR

This paper explores how magnetic force microscopy can detect nonmagnetic metal thin films by analyzing tip oscillations, enabling contactless measurement of properties like sheet resistivity at the nanoscale.

## Contribution

It provides a theoretical framework for detecting nonmagnetic metals with MFM and identifies optimal oscillation frequencies for sensitive measurements.

## Key findings

- Good agreement between theory and experiment.
- Detection sensitivity depends on oscillation frequency.
- Resonance frequency shifts can indicate metal presence.

## Abstract

Magnetic force microscopy (MFM) allows detection of stray magnetic fields around magnetic materials and the two-dimensional visualization of these fields. This paper presents a theoretical analysis of the oscillations of an MFM tip above a thin film of nonmagnetic metal. The results show good agreement with experimental data obtained by varying the tip height. The phenomenon analyzed here can be applied as a "metal detector" at the nanometer scale and for contactless measurement of sheet resistivity. The detection sensitivity is obtained as a function of oscillation frequency, thus allowing determination of the best frequency for phase-shift measurement. The shift in resonance frequency due to the presence of a nonmagnetic metal is also discussed.