Regensburg 2010 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 10: Measuring Devices, Cryotechnique: Poster Session
TT 10.6: Poster
Monday, March 22, 2010, 14:00–18:00, Poster A
SQUID submicroemu ferromagnetic and superconducting signals embedded in much larger diamagnetic ones — •Ana Ballestar1,2, Annette Setzer2, Pablo Esquinazi2, and Nicolas Garcia1 — 1Laboratorio de Fisica de Sistemas Pequeños (LFSPyN), Consejo Superior de Investigaciones Científicas (CSIC), Serrano 144, 28006 Madrid, Spain — 2Division of Superconductivity and Magnetism Universität Leipzig, Linnéstraße 5, D-04103 Leipzig, Germany
Commercial superconducting quantum interferometer devices (SQUID) are widely used to measure small magnetic signals. In general, the SQUID signal is taken as a proof for the existence of ferromagnetic or superconducting phases in the samples. When magnetic moment signals below 1 µemu are present the situation is complicated due to the intrinsic resolution limits of the magnetometer. Measuring the response of a superconducting Pb-thin film on the surface of a graphite sample we were able to show that the sub-µemu signals of the ferromagnetic (from graphite) and superconducting (from Pb) phases are very well measured even when they are embedded in diamagnetic signals in the range of 4 to 30 µemu. Our work proves that it is possible to work with a commercial SQUID down to sub-µemu region after the subtraction of a large background signal coming from the same sample.