Dr. John Cerne

Photo of Associate Professor John Cerne  

Associate Professor, Ph.D. UC Santa Barbara (1996)

Office: 128 Fronczak Hall,  (716) 645-2542
Lab: 103 Fronczak Hall,  (716) 645-2006
Email: jcerne@buffalo.edu
link to personal website for more info

Education

  Ph.D. -- University of California, Santa Barbara (1996)
B.S. -- Princeton University (1990)

Research Interests

  The discovery of high-temperature superconductors (HTSC) has challenged many well-accepted principles of how metals (typically, Fermi liquids) behave. Though showing metallic behavior, these materials have a number of fundamentally anomalous properties that have defied explanation for the last decade. One of the most striking anomalies is the DC Hall effect, where the scattering rate associated with transverse Hall current appears to be fundamentally different from the scattering rate associated with longitudinal current. A rich variety of models is consistent with the DC Hall measurements; however, these models predict different behavior at higher frequencies. Thus, Hall measurements at finite frequencies are essential for determining which models have the most promise for providing a complete understanding of HTSC response. We have extended Hall measurement into the infrared frequency range by using sensitive optical polarization modulation techniques. This novel measurement not only allows a critical test of the proposed models for HTSC materials, but may also shed light on the origin of the unusual properties found in other classes of materials, such as the ruthenates and colossal magnetic resistance oxides, which also show evidence for non-Fermi liquid behavior.
Polarimetry techniques also can be applied to study wide-band- gap and diluted magnetic semiconductors. Reflection and transmission anisotropy measurements provide a versatile and sensitive probe of a variety of parameters (e.g., strain, magnetization, composition, doping, etc.) that are critical to these materials. One unique advantage of these techniques is that they can monitor the properties of the material during growth. This research will address the technical challenges that are facing the growth of these materials as well as basic physical questions.

Selected Publications

  1. "Photo-thermal transitions of magneto-excitons in quantum wells", J. Cerne, J. Kono, M. Su, and M.S. Sherwin, Phys. Rev. B66, 201305 (2002).
  2. "AC Hall effect in YBCO: Temperature and frequency dependence of Hall scattering", J. Cerne, M. Grayson, D.C Schmadel, H. D. Drew, R. Hughes, J.S. Preston, and P.J. Kung, Physica B284, 941 (2000).
  3. "Infrared Hall effect in high Tc superconductors: Evidence for non-Fermi liquid Hall scattering", J. Cerne, M. Grayson, D.C Schmadel, G.S. Jenkins, H. D. Drew, R. Hughes, J.S. Preston, and P.J. Kung, Phys. Rev. Lett. 84, 3418 (2000).
  4. "Mid-infrared Hall effect in thin-film metals: Probing the Fermi surface anisotrophy in Au and Cu", J. Cerne, D.C. Schmadel, M. Grayson, G.S. Jenkins, J.R. Simpson, and H.D. Drew, Phys. Rev. B61, 8133 (2000).
  5. "Optical Conductivity of Maganites: Crossover from Jahn-Teller Small Polaron to Coherent Transport in the Ferromagnetic State", M. Quijada, J. Cerne, R. Simpson, H.D. Drew, K. H. Ahn, A.J. Millis, R. Shreekala, R. Ramesh, M. Rajeswari, and T. Venkatesan, Phys. Rev. B58, 16093 (1998).