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Biographical Sketch
Prof. Castner received his Ph.D. in Physics from the University of Illinois-Urbana in 1958. After 5 years at the General Electric Research and Development Center in Schenectady he joined the University in 1963 as an Associate Professor of Physics. He was promoted to Professor in 1970. He became Professor Emeritus in 1991 after serving nearly two years as a Program Director at the National Science Foundation in the Division of Materials Research. Prof. Castner was a Guggenheim Fellow at the ETH in Zurich (1969-70) and was elected Fellow of the American Physical Society in 1971. At the NSF, he received an Outstanding Performance Award in 1991.
Research
Prof. Castner's research is in the area of Experimental Condensed Matter Physics. His research in recent years has been on the metal-insulator transition. This is a zero temperature, quantum phase transition, commonly observed in doped semiconductors, particularly n-type Si. Earlier studied used measurements of the dielectric response on the insulating side, and measurements of conductivity on both metal and insulating sides, in order to establish the critical behavior of "Mott variable range hopping." Magnetic resonance measurements documented the Poisson statistics of donor clusters and the critical behavior of the conduction electron spin resonance line width. Other measurements have included the frequency-dependent conductivity in the microwave range. Recent measurements include the antiferromagnetic resonance of the nearly ideal Heisenberg antiferromagnet determining the value of the order parameter exponent in the spin-flop phase very close to the Neel temperature. Current studies will involve measure of the dielectric response of barely metallic n-type Si samples in addition to the determination of the field dependence of the CESR linewidth of barely metallic samples. The present studies will concentrate on the microwave properties of doped Si near the critical density, but may also be extended to the cuprates and the manganates using a Cu helical resonator.
Recent Publications
- Deconvolution of Activated and Variable Range Hopping Conduction for Barely Insulating Arsenic-doped Silicon
T.G.Castner and W.N.Shafarman
Physical Review B B60, 14182 (1999)
- Resolution of the Scaling Exponent Puzzle for Weakly Compensated Crystalline Silicon and Germanium Metal-Insulator Systems
T.G.Castner
Physical Review Letters 84, 1539 (2000)
- A Nearly Universal Critical Conductivity for Semiconductor-Metal Alloys
T.G.Castner
Physical Review Letters 84, 2905 (2000)
- Variable Range Hopping in the Critical Regime
T.G.Castner
Physical Review B B61, 16596 (2000)
- Critical Conductivity for Semiconductor-Metal Alloys
T.G.Castner
Physica B 284-288, 1679 (2000)
(abstract)
For further details, go to Prof. Castner's home page at: http://spider.pas.rochester.edu/mainFrame/people/pages/Castner_Theodore_G.html
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