John R. Clem
The goal of my current research program has been to make significant theoretical advances con cerning the electrodynamic behavior of current-carrying superconductors subjected to mag netic fields. Recently I have been giving greatest attention to the high-temperature superconduc tors, first discovered in 1986. Problems that I am particularly interested in include flux pinning, critical currents, flux flow, ac losses, noise, spiral and intersecting vortices, instabilities, surface and interface effects, proximity effects, and two- and three-dimensional arrays of Josephson junctions. Although my focus is generally on the solution of fundamental problems, I always have been strongly motivated by the fact that a solidly based theoretical understanding of the above interrelated subjects is needed to make the most effective use of superconductors in various applications, both large-scale (e.g., wire and tapes for high-field magnets and power transmission lines) and small-scale (e.g., filters, resonators, and Josephson devices for use in sensitive detectors and logic devices.)
(Chronologically most recent on top)Education
- Ph.D. Physics, University of Illinois, 1965
- M.S. Physics, University of Illinois, 1962
- B.S. Engineering Physics, University of Illinois, 1960
(Chronologically most recent on top)Professional Appointments
- 2001 - 2010 Contract Associate (1/4 time), Ames Laboratory
- 1992 - 1993 Visiting Scientist, Electric Power Research Institute, Palo Alto, CA
- 1992 - 1993 Visiting Professor of Applied Physics, Stanford University, Stanford, CA
- 1985 - 1986 Visiting Scientist, IBM Thomas J. Watson Research Center, Yorktown Heights, NY
- 1982 - 1985 Chairman, Department of Physics, Iowa State University
- 1975 - 2001 Senior Physicist, Ames Laboratory
- 1974 - 1975 Fulbright Research Fellow, Kernforschungsanlage Jülich, Germany
- 1971 - 2010 Various appointments as Consultant at Los Alamos National Laboratory, Argonne National Laboratory, Brookhaven National Laboratory, IBM Thomas J. Watson Research Center, Allied-Signal Aerospace Company, Underground Systems, Inc., American Superconductor Corporation, Pirelli Cable Corporation
- 1970 - 1975 Physicist, Ames Laboratory
- 1967 - 1970 Associate Physicist, Ames Laboratory
- 1966 - 1967 Visiting Research Fellow, Technical University, Munich, Germany
- 1965 - 1966 Research Associate, University of Maryland
(Chronologically most recent on top)Honors & Awards
- 2010 American Physical Society Outstanding Referee
- 2004 Fellow, Institute of Physics, London
- 1999 Most Valuable Instructor (teaching award from graduate students in the Iowa State University Department of Physics and Astronomy, 2000)
- 1997 Phi Kappa Phi Centennial Medalist, Iowa State University Chapter of Phi Kappa Phi
- 1991 Teaching Award from Graduate Students in the Iowa State University Department of Physics and Astronomy
- 1990 For contributions to the superconductivity community, Applied Superconductivity Conference, Inc.
- 1988 DOE Annual Award for Sustained Outstanding Research in Solid State Physics
- American Association of University Professors
- 1982 Fellow, American Physical Society
(Chronologically most recent on top)Publications with the Ames Laboratory
Clem J R . 2013. Inductances and attenuation constant for a thin-film superconducting coplanar waveguide resonator. Journal of Applied Physics. 113:013910.
Hortensius H L; Driessen E F C; Klapwijk T M; Berggren K K; Clem J R . 2012. Critical-current reduction in thin superconducting wires due to current crowding. Applied Physics Letters. 100:182602.
Clem J R; Mawatari Y; Berdiyorov G R; Peeters F M . 2012. Predicted field-dependent increase of critical currents in asymmetric superconducting nanocircuits. Physical Review B. 85:144511.
Clem J R; Berggren K K . 2011. Geometry-dependent critical currents in superconducting nanocircuits. Physical Review B. 84:174510.
Clem J R . 2011. Effect of nearby Pearl vortices upon the I(c) versus B characteristics of planar Josephson junctions in thin and narrow superconducting strips. Physical Review B. 84:134502.
Jia Y; Welp U; Crabtree G W; Kwok W K; Malozemoff A P; Rupich M W; Fleshler S; Clem J R . 2011. Microstructure dependence of the c-axis critical current density in second-generation YBCO tapes. Journal of Applied Physics. 110:083923.
Clem J R . 2011. Theory of flux cutting and flux transport at the critical current of a type-II superconducting cylindrical wire. Physical Review B. 83:214511.