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Magnetic nanoparticle detection using nano-SQUID sensors.

Hao, L; Cox, D; See, P; Gallop, J C; Kazakova, O (2010) Magnetic nanoparticle detection using nano-SQUID sensors. J. Phys. D, Appl. Phys., 43 (47). 474004

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Magnetic nanoparticles have been intensively studied for decades. Recently, individual particles and nanowires have been examined using various methods, including magnetoresistive detectors, dc nano-SQUID and Hall magnetometry. Here we demonstrate detection of a single bead (diameter ~120 nm, moment ~10^4 uB) using an Nb dc SQUID with the loop size in the range of 250-800 nm operational at T<10 K. The system noise was minimized down to 0.2 uF0/Hz^1/2 using a cryogenic SQUID series array pre-amplifier. Initial measurements of an individual magnetic nanoparticle were performed and a clear change of the noise spectra of the nano-SQUID was detected at low frequencies in the presence of the nanoparticle. Thus, we demonstrate a magnetic sensor based on a dc nano-SQUID and enabling detection of small moments (potentially down to a few electron spins). Such a sensor is of considerable significance for nanomagnetic metrology and quantum information processing based on spin systems.

Item Type: Article
Keywords: nano-SQUID, magnetic nanoparticle
Subjects: Nanoscience
Nanoscience > Nano-Materials
Last Modified: 02 Feb 2018 13:15
URI: http://eprintspublications.npl.co.uk/id/eprint/4811

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