Thomas Gredig

Assistant Professor, Condensed Matter Experiment

Ph.D. Physics, University of Minnesota, Twin Cities, 2002
M.S. Physics, University of Minnesota, Twin Cities, 1998

Location:
Office: Hall of Science (HSCI), Room 272d

California State University, Long Beach
Department of Physics Astronomy
1250 Bellflower Blvd.
Long Beach, CA 90840-9505

Phone: (562) 985-4922
Fax: (562) 985-7924
Email: tgredig@csulb.edu

Webpage :
http://www.csulb.edu/~tgredig/

Research Interests:
Condensed Matter Experiment, Thin Films, Nanomagnetism, Organic Semiconductors, Organic Field-Effect Transistors, Thin Film Crystallography, Exchange Bias
Organic Semiconductors - Phthalocyanines belong to a diverse family of organic semiconductors. At the center of such a molecule is usually a metal ion, such as Cu, Fe, Co, or Zn, for example. Phthalocyanines are currently used as dyes (jeans, CD-R), gas sensors ("noses"), and photoconductors in copy machines. I am interested in understanding the structural properties, charge transport properties, magnetic properties of iron-phthalocyanine (FeC 32 N 8 H 16 ), and the design of novel gas sensors.

Exchange Bias - it refers to the interaction at the interface between a ferromagnet and an antiferromagnet of a thin film. Applications include magnetic read-heads of commercial hard disc drives. Through cooling such a bilayer in a magnetic field below the Néel temperature of the antiferromagnet, a magnetic unidirectional anisotropy is induced. This anisotropy pins the ferromagnet in the cooling field direction, and breaks the symmetry of the magnetic hysteresis loop. I have made contributions to the understanding of the magnetization reversal process in exchange biased system, the training effect, and the local pinning field strength in Co/CoO bilayers.

Magnetic Vortices - They can be nanodots larger than a single magnetic domain, but not large enough for a magnetic domain wall to form. I have made magnetic Co vortices that typically measure 400 to 500nm in diameter. I am interested in understanding the interactions of magnetic vortices with a superconductor.

Superconductivity - I am interested in understanding the effect of white light illumination on the properties of high-T c superconductors. In the past, I have compared oxygen deficient YBCO, LCMO, and bilayers of YBCO/LCMO and studied the effect of light on the superconductor transition temperature.