Magnetic force sensing using a self-assembled nanowire

TL;DR

This paper introduces a novel scanning magnetic force sensor using a self-assembled GaAs nanowire with a magnetic MnAs tip, capable of high-resolution imaging of weak magnetic fields at the nanoscale.

Contribution

It demonstrates the fabrication, characterization, and application of a nanowire-based magnetic force sensor with high sensitivity and potential for nanoscale magnetic imaging.

Findings

Nanowires exhibit distinct magnetic configurations including vortices.

The sensor can detect magnetic fields from lithographically patterned wires.

High force sensitivity enables imaging of weak magnetic field patterns.

Abstract

We present a scanning magnetic force sensor based on an individual magnet-tipped GaAs nanowire (NW) grown by molecular beam epitaxy. Its magnetic tip consists of a final segment of single-crystal MnAs formed by sequential crystallization of the liquid Ga catalyst droplet. We characterize the mechanical and magnetic properties of such NWs by measuring their flexural mechanical response in an applied magnetic field. Comparison with numerical simulations allows the identification of their equilibrium magnetization configurations, which in some cases include magnetic vortices. To determine a NW's performance as a magnetic scanning probe, we measure its response to the field profile of a lithographically patterned current-carrying wire. The NWs' tiny tips and their high force sensitivity make them promising for imaging weak magnetic field patterns on the nanometer-scale, as required for mapping mesoscopic transport and spin textures or in nanometer-scale magnetic resonance.