We demonstrate the use of the magnetic-field-dependence of highly spatially confined, GHz-frequency ferromagnetic resonances in a ferromagnetic nanostructure for the detection of adsorbed magnetic nanoparticles. This is achieved in a large area magnonic crystal consisting of a thin ferromagnetic film containing a periodic array of closely spaced, nano-scale anti-dots. Stray fields from nanoparticles within the anti-dots modify resonant dynamic magnetisation modes in the surrounding magnonic crystal, generating easily measurable resonance peak shifts. The shifts are comparable to the resonance linewidths for high anti-dot filling fractions with their signs and magnitudes dependent upon the modes' localisations (in agreement with micromagnetic simulation results). This is a highly encouraging result for the development of frequency-based nanoparticle detectors for high speed nano-scale biosensing.
@article{arxiv.1501.01171,
title = {Sensing magnetic nanoparticles using nano-confined ferromagnetic resonances in a magnonic crystal},
author = {Peter Metaxas and Manu Sushruth and Ryan Begley and Junjia Ding and Robert Woodward and Ivan Maksymov and Maximilian Albert and Weiwei Wang and Hans Fangohr and Adekunle Adeyeye and Mikhail Kostylev},
journal= {arXiv preprint arXiv:1501.01171},
year = {2015}
}