Theodore G. Castner

Professor of Physics, Emeritus
PhD in Physics, University of Illinois, Urbana-Champaign, 1958

463 Bausch & Lomb Hall
(585) 275-8577
Fax: (585) 273-3237

Research Overview

Professor 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. He 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.

Selected 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
    Physical Review Letters 84, 1539 (2000)
  • A Nearly Universal Critical Conductivity for Semiconductor-Metal Alloys
    Physical Review Letters 84, 2905 (2000)
  • Variable Range Hopping in the Critical Regime
    Physical Review B B61, 16596 (2000)
  • Critical Conductivity for Semiconductor-Metal Alloys
    Physica B 284-288, 1679 (2000)