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Site Details Related Sites BNL Basic Energy Sciences Directorate Condensed Matter Physics & Materials Science Center for Functional Nanomaterials National Synchrotron Light Source National Synchrotron Light Source II Other Information |
Christopher C. Homes
Physicist, Electron Spectroscopy Group(Infrared and Terahertz Spectroscopy)
Fellow, American Physical Society
Condensed Matter Physics & Materials Science Dept. - Bldg. 510BBrookhaven National Laboratory20 Pennsylvania StreetP.O. Box 5000Upton, NY 11973-5000
Tel: (631) 344-7579 Fax: (631) 344-2739 email: homes@bnl.gov
Welcome to my personal home page! I am a physicist in the Electron Spectroscopy Group in the Condensed Matter Physics and Materials Science Department at Brookhaven National Laboratory, where I study the interaction of light with solids, and pretty much anything else too slow to get out of the way. In particular, I use infrared radiation from conventional black-body sources, as well as from the National Synchrotron Light Source at the U12IR beam line. If you would like to learn more about the fundamentals of infrared spectroscopy, you can view a PDF file of a monograph Fourier-transform infrared spectroscopy (recently revised) that I am working on, but have not yet finished (you will need Adobe Acrobat Reader to view this document). I was once (but no longer am) involved with a software company called Idelix that developed advanced interface technologies, providing enhancements in mobile, desktop, Web-based applications, and is based in Vancouver, British Columbia; this company has since been reconstituted and is now known as Lat49. Finally, a link to the old picture that used to be here of our cat Kira helping me with a physics problem.
Education, professional experience
Honours and awards
Research Interests & Experimental Program
I am primarily interested in using infrared radiation to probe the electronic and vibrational properties of solids. The reflectance of a material is a complex quantity, with an amplitude and a phase. During a typical experiment, we only measure the reflected amplitude of the radiation. However, if the reflectance is measured over a wide enough range, then it is possible using the Kramers-Kronig relation to calculate the phase: once the amplitude and phase are known, then other optical response functions may be calculated, specifically the real part of the complex conductivity. In the past I have used this technique to study a wide variety of materials, including the low-dimensional organic conductors and superconductors, quasicrystals, C60, collosal magnetoresistance materials (CMR's), high-dielectric response materials and the high-temperature cuprate superconductors.
The current focus of my research is on electronic phenomena in strongly correlated electron systems. We have extended our infrared techniques well into the terahertz region (1 THz = 33.3 cm-1), allowing the low-energy collective modes of these systems to be studied. Of particular interest are
My current projects involve examining the polarized optical properties detwinned single crystals of YBa2Cu3O6+x (YBCO) at a variety of doping levels in the normal and superconducting states, with particular emphasis placed on the underdoped region. The original high-temperature superconductor La2-xBaxCuO4 (LBCO) material is also being studied for several chemical dopings, including the magic x~1/8 concentration, where the critical temperature is observed to be strongly suppressed due to the formation of charge- and spin-stripe order; the notion of competing order parameters is also being examined in the nickelate La2NiO4+d and the Sr14-xCaxCu24O41 two-leg ladder systems, as well as in the simpler Sr2CuO3 quasi-one dimensional material. The electron-doped systems (Nd,Pr)2-xCexCuO4 are also being studied to determine of electron-hole symmetry exists within the cuprates, as well as if the underdoped region of the phase diagram, which is rather difficult to achieve in the electron-doped materials, is similar to that of the hole-doped materials. In all of the infrared studies, we are also trying to develop methods of determining the spectral function and to compare it with information about the spectral function that may be determined from ARPES studies of these materials.
We are also interested in optical properties of ultra-thin films of Pb and in solvated-electron systems. This type of experiment blends ultra-high vacuum, low temperature, and optical techniques to grow a film in situ at cryogenic temperatures and measure the optical properties simultaneously. These studies are providing information about the nature of transport in disordered granular systems. Future work in this area may also involve work on graphene.
Recent Publications (full publication list)
Book Chapters
Other notable works...
Useful linksBNL and NSLS Infrared links:Physics related links:Optics and superconductivity links:
Personal Musings
Whenever you advise a ruler in the way of the Tao,
Last modified: Monday, May 16, 2011 02:26 PM. |