April 11, Russell Giannetta, University of Illinois at Champaign/Urbana

rwg33:00 PM in Room 205, 8 St. Mary’s Street

Refreshments served at 2:45 PM

Using an LC Oscillator to Pry Open Superconductivity

Abstract: The order parameter is the basic quantity characterizing the quantum state of a superconductor. My talk will focus on the use of London penetration depth measurements to access the order parameter. I will discuss a simple but powerful tunnel diode oscillator method to measure the penetration depth. Using examples from copper oxide, organic and iron-based superconductors I will explain how to tell if the order parameter has nodes, whether it changes sign and whether superconducting order lives on multiple Fermi surface sheets. If time permits, I will discuss how penetration depth measurements can also reveal phenomena such as electronic phase separation and quantum criticality.

Biography: Prof. Giannetta received his PhD in physics in 1980 from Cornell University, working on NMR and ultrasonic measurements of superfluid 3He. He spent two years as a postdoc at Bell Telephone Labs and was an assistant professor at Princeton University during which time he studied instabilities and Wigner crystallization of electrons on the surface of liquid helium. He began working on superconductivity as a faculty member at City College of New York. He moved to the University of Illinois in 1993 and has since worked on quantum transport in semiconductor nanostructures, London penetration depth and NMR measurements of superconducting materials.

Faculty Host: David Bishop

Student Host: Shizhao Su