Optimizing the flux coupling between a nanoSQUID and a magnetic particle using atomic force microscope nanolithography

TL;DR

This paper demonstrates how atomic force microscope nanolithography can precisely engineer and align Niobium-based nanoSQUIDs with magnetic particles, improving their sensitivity and enabling detailed studies of magnetization switching.

Contribution

It introduces a novel AFM-based nanolithography technique for fabricating and aligning nanoSQUIDs with magnetic particles, enhancing device performance and measurement precision.

Findings

Enhanced magnetic field modulation and sensitivity of the nanoSQUIDs.

Precise alignment of weak-links with ferromagnetic particles.

Successful observation of magnetization switching behavior.

Abstract

We present results of Niobium based SQUID magnetometers for which the weak-links are engineered by the local oxidation of thin films using an Atomic Force Microscope (AFM). Firstly, we show that this technique allows the creation of variable thickness bridges with 10 nm lateral resolution. Precise control of the weak-link milling is offered by the possibility to realtime monitor weak-link conductance. Such a process is shown to enhance the magnetic field modulation hence the sensitivity of the magnetometer. Secondly, AFM lithography is used to provide a precise alignment of NanoSQUID weak-links with respect to a ferromagnetic iron dot. The magnetization switching of the near-field coupled particle is studied as a junction of the applied magnetic field direction.