Colloquium: Prof. Allen Goldman
Prof. Allen M. Goldman
School of Physics and Astronomy
University of Minnesota
Friday Apr 24, 2015, 4:00–5:00pm, 211 Witmer Hall. Refreshments at 3:30pm.
Electrostatic Modification of Superconductivity
Recently there has been major progress in developing field-effect-transistor-like structures that can be used to modify the carrier concentrations of thin films of superconducting materials. These structures include simple capacitor configurations employing high dielectric constant insulators as well as configurations involving ionic liquids or ion gels, which function as electric double layer transistors. These configurations have been used to study quantum phase transitions such as the superconductor-insulator transition in ultrathin films of disordered metals and high temperature superconductors, as well as to search for new superconductors. In this talk the operation of these structures will be explained along with a discussion of the advantages and disadvantages of electrostatic gating relative to other techniques used to manipulate superconductivity. The major results of the study of quantum critical behavior of superconductors using these structures will be presented.
Allen Goldman joined the School of Physics and Astronomy in 1965. In the 1970's, his group discovered the existence of gapless order-parameter collective modes, now known as Carlson-Goldman modes, in superconducting films. He was one of the pioneers in the physics of two-dimensional systems, including the Kosterlitz-Thouless transition in superconducting thin films and networks. In the mid-1980's, he and his group developed a new means for preparing extremely thin quench-condensed superconducting films, and his subsequent research has led to a profound understanding of the onset of superconductivity at zero temperature. His demonstration that the superconductor-insulator transition in thin films has universal properties has made it one of the canonical examples of a quantum phase transition. He has also advanced the materials physics of superconductivity by perfecting new techniques for the growth of high-temperature superconductors by molecular beam epitaxy. 
During his career at the University of Minnesota, Allen has mentored over 50 graduate students and 15 postdoctoral associates. He was appointed Professor of Physics in 1975, an Institute of Technology Distinguished Professor in 1992, and was named a Regents Professor, the University of Minnesota's highest distinction, in 2008. Among other honors, Allen is a fellow of the American Association for Advancement of Science and the American Physical Society. In recognition of his research on superconducting thin films, he was awarded the Fritz London Memorial Prize in 2002, and he was elected to the National Academy of Sciences in 2007.  M ost recently, he won the 2015 Oliver E. Buckley Condensed Matter Physics Prize for his "discoveries and pioneering investigations of the superconductor-insulator transition, a paradigm for quantum phase transitions."