Dr. John Cerne
Professor, Ph.D. UC Santa Barbara (1996)
Office: 128 Fronczak Hall, (716) 645-2542
Lab: 103 Fronczak Hall, (716) 645-2006
link to personal website for more info
Ph.D. -- University of California, Santa Barbara (1996)
B.S. -- Princeton University (1990)
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.
- "Photo-thermal transitions of magneto-excitons in quantum wells", J. Cerne, J. Kono, M. Su, and M.S. Sherwin, Phys. Rev. B66, 201305 (2002).
- "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).
- "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).
- "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).
- "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).