Probing the magnetic moment of FePt micromagnets prepared by Focused Ion Beam milling

TL;DR

This study measures the magnetic moment degradation of FePt micromagnets after FIB milling, showing 70% preservation, which is significant for applications like atom trapping and MRFM.

Contribution

The paper provides the first quantitative measurement of magnetic moment retention in FePt micromagnets post-FIB milling, highlighting its implications for magnetic applications.

Findings

70% of magnetic moment preserved after FIB milling

Magnetic moment measured as approximately 1.1 x 10^-12 Am^2

Results impact design of magnetic devices for atom trapping and MRFM

Abstract

We investigate the degradation of the magnetic moment of a 300 nm thick FePt film induced by Focused Ion Beam (FIB) milling. A $1~\mu \mathrm{m} \times 8~\mu \mathrm{m}$ rod is milled out of a film by a FIB process and is attached to a cantilever by electron beam induced deposition. Its magnetic moment is determined by frequency-shift cantilever magnetometry. We find that the magnetic moment of the rod is $\mu = 1.1 \pm 0.1 \times 10 ^{-12} \mathrm{Am}^2$, which implies that 70% of the magnetic moment is preserved during the FIB milling process. This result has important implications for atom trapping and magnetic resonance force microscopy (MRFM), that are addressed in this paper.