Dresden 2017 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 48: Superconductivity: Tunnelling, Josephson Junctions, SQUIDs 2
TT 48.4: Vortrag
Mittwoch, 22. März 2017, 15:45–16:00, HSZ 201
NanoSQUID magnetometry of individual cobalt nanoparticles — •Benedikt Müller1, Maria José Martínez-Pérez1, Dennis Schwebius1, Dana Korinski1, Jianxin Lin1, Reinhold Kleiner1, Javier Sesé2, and Dieter Koelle1 — 1Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Germany — 2Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza, Spain
We demonstrate the operation of low-noise nanoSQUIDs based on the high critical field and high critical temperature superconductor YBa2Cu3O7 (YBCO) as ultra-sensitive magnetometers for single magnetic nanoparticles (MNPs) [1]. The nanoSQUIDs contain grain boundary Josephson junctions and are patterned by focused ion beam milling. They can be operated over extremely broad ranges of applied magnetic field (up to ∼ 1 T) and temperature (0.3 K < T < 80 K). Cobalt MNPs with typical size of several tens of nm have been grown directly on top of the sensors by focused electron beam induced deposition. This allows us to investigate the magnetization reversal of individual MNPs with magnetic moments (1 − 30) × 106 µB. The magnetization reversal appears to be thermally activated over an energy barrier, which has been quantified for the (quasi) single-domain particles. These measurements demonstrate that YBCO nanoSQUIDs are exceptional magnetometers for the investigation of individual nanomagnets.
[1] M. J. Martínez-Pérez et al., Supercond. Sci. Technol. 30, 024003 (2016)