Dresden 2011 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 46: SC: Tunneling, Josephson Junctions, SQUIDs 1
TT 46.6: Talk
Thursday, March 17, 2011, 12:00–12:15, HSZ 301
Sensitive dc SQUIDs for detection of small spin systems — •R. Wölbing1, J. Nagel1, M. Kemmler1, K. Konovalenko1, M. Turad1, R. Werner1, R. Kleiner1, D. Koelle1, O. Kieler2, T Weimann2, J. Kohlmann2, A. Zorin2, E. Kleisz3, S. Menzel3, B. Büchner3, and R. Klingeler3 — 1Physikalisches Institut - Experimentalphysik II and Center for Collective Quantum Phenomena, Universität Tübingen, 72076 Tübingen, Germany — 2Fachbereich 2.4 "Quantenelektronik", Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany — 3Leibnitz-Institut für Festkörper- und Werkstoffforschung (IFW) Dresden, 01171 Dresden, Germany
Investigation on small spin systems, e.g. macromolecules, require ultrasensitive devices for sensing the magnetization reversal of such particles with the ultimate goal of single spin flip detection. For this purpose we examine submicron dimension SQUIDs, which can detect the magnetization reversal of small spin particles directly in strong magnetic fields. We fabricated dc SQUIDs based on Nb/HfTi/Nb Josephson junctions with areas down to 200 nm x 200 nm, as well as on YBa2Cu3O7 (YBCO) grain boundary junctions (GBJs) with linewidths down to 80 nm. The critical current densities for both types of junctions are relatively large (jc>105A/cm2 at 4.2 K), which provides high critical currents even for submicron sized junctions. The Nb/HfTi/Nb and the YBCO SQUIDs have been characterized by electric transport and noise measurements at low and high fields up to the tesla range, showing low noise performance.