Jon Lawrence

Picture of Jon Lawrence
Professor, Physics & Astronomy
School of Physical Sciences
PH.D., University of Rochester
Phone: (949) 824-5580
Fax: (949) 824-2174
University of California, Irvine
2176 Frederick Reines Hall
Mail Code: 4575
Irvine, CA 92697
Research Interests
Experimental studies of heavy fermion compounds including crystal growth and characterization, thermodynamics, and spectroscopies (neutron scattering and X-ray absorption).
Research Abstract
Heavy fermion compounds are rare-earth-based materials with many unusual properties. Most of the compounds behave as metals at low temperatures, but with anomalously large effective masses so that the Pauli susceptibilities and coefficients of specific heat are large. Others order magnetically, but with extremely small ordered moments (0.01┬ÁB); some are semiconductors with very small energy gaps (23meV); and some are superconductors with unusual symmetries for the Cooper pairs. My research has several stages for studying heavy fermion compounds.

The first stage is preparation of polycrystalline and single-crystal samples by conventional techniques (arc-melting; flux growth) with characterization by x-ray diffraction and metallography. The second is measurement of basic thermodynamic properties such as the magnetic susceptibility, specific heat, thermal expansion coefficient, and electric resistivity, over a broad range of temperatures, pressures, and magnetic fields. These experiments are performed primarily in the Condensed Matter Group at Los Alamos, with which I have an active collaboration.

The third stage involves spectroscopic experiments, which are carried out in collaboration with scientists at the national labs. These measurements include neutron scattering experiments at reactor sources (e.g. the HFIR at Oak Ridge) and at spallation sources (e.g. IPNS at Argonne National Lab and LANSCE at Los Alamos) and x-ray absorption experiments (e.g. at the Stanford synchrotron SSRL). These experiments provide key microscopic information about heavy fermion compounds.
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