2009 Advanced Laboratories Conference Abstract Detail Page

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Abstract Title: Resistivity Measurements and Observation of Transition to Superconducting State
Abstract: Superconductivity is a hot topic at all levels and seeing the drop of resistance to zero on a student prepared sample(s) is a special experience. Here, we present the use of four point contacts onto small cross-section samples (wire or other) of elements (In, Pb, Sn ...) and NbTi and varying lengths (several cm) to measure the resistivity (resistance) and its temperature dependence. The samples are obtained from off-the-shelf wire or sheet stock and then prepared to obtain sample resistance of 0.1 – 10 Ohms which is easily and accurately measured with either DC or AC techniques. Using lock-in-detection, the AC method has nano-Volt resolution which, with milli-Ampere floating excitation current source, leads to the detection of micro-Ohm resistance change at any temperature. This laboratory experiment lends itself to practicing many aspects, techniques and skills of experimental physics from the four-point probe, cryogen handling, thermometry, data acquisition, error analysis and curve fitting (data manipulation) to obtaining the materials transport parameters, to safety procedures in sample preparation. The resistivity (resistance) temperature dependence and the residual resistivity ratio (RRR) do shed light on materials process issues such as alloying and cold working.  Solid state physics concepts and ideas like Matheson's rule, phonons and their effect on resistivity temperature dependence are demonstrated and studied, as well as the transition from normal conductor to superconductor state.
Abstract Type: Poster
Contributed Poster: Download the Contributed Poster
Session: Session IX - Effective Experiments Poster Session

Author/Organizer Information

Primary Contact: Mohammed Z Tahar
State University of New York College at Brockport
350 New Campus Drive
Brokcport, NY 14420
Phone: 5853955704
Fax: 5853955805