[Cerne Photo]

John Cerne

Assistant Professor


Condensed Matter Experiment

A.B., 1990, Princeton University
Ph.D., 1996, University of California, Santa Barbara

Office : 128 Fronczak Hall
Lab : 103 Fronczak Hall
Phone : 716-645-2017 ext. 121
FAX : 716-645-2507
Email : jcerne@buffalo.edu

Research Interests:

The discovery of high temperature superconductors (HTS) 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 are 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 HTS 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 HTS 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.

PCCO conductivity.

 

Educational Interests:

My goal is to make learning and teaching more interactive and interesting.  Students learn by thinking and making connections, and unfortunately not much time is dedicated to thes processes in traditional lectures.  Here are a few examples that I have develeoped in an attempt to engage students in physics lectures.  Please note that this part of my website is still under development.

Coin Toss Demo Results.

Multitrack timer used in lecture

Example of constant velocity demo.

Magneto-polarimetry manual for Advanced Lab.

Hall effect in high temperature superconductors manual for Advanced Lab.

Polarized light demonstration.

Change in light polarization due to a sample.

Conceptual Learning Approach to Waves- CLAW; Getting a physical grasp on waves and polarized light

Group velocity demo, v_group=1.7v_phase

Group velocity demo, v_group=0.1v_phase

Group velocity demo, v_group=0.4v_phase

Group velocity demo, v_group=0.7v_phase

 

 

More links:

Link to the UB Chapter of the Society of Physics Students

If the pdf files do not load properly on your web browser, try right clicking on the link and saving it to your local hard drive.

Selected Publications:

Physics Home Page.

This web page is maintained by John Cerne