Ted Barnes
Victor Barzykin
Tom Callcott
Bob Compton
Pengcheng Dai
Adolfo Eguiluz
David Mandrus
Ward Plummer
John Quinn
Jim Thompson
Hanno Weitering
Zhenyu Zhang
Dr. Pengcheng Dai
Associate Professor/UT-ORNL Joint FacultyOffice: 407-A Nielsen Physics Building/ORNL
Phone: (865) 974-1509 or (865) 574-5233
E-mail: piq@ornl.gov
Dr. Dai's Research Group: http://pdai.phys.utk.edu/
For many decades it has been accepted that the low-temperature transport properties of most semiconductors and metals can be described by Landau's Fermi liquid theory, where the states of an interacting electron gas in the material can be put into an one-to-one correspondence with noninteracting gas of "quasiparticles." The properties of recently discovered new (and in some cases, old) materials appear to defy Landau's description and are dominated by strong electron-electron, electron-lattice, and electron-orbital interaction effects. Examples for this class of so-called "highly correlated electron materials" include the high-transition-temperature copper oxide superconductors, heavy fermion metals, and colossal magneto-resistance manganese oxides. Clearly, highly correlated electron systems present us with some of the deepest intellectual challenges in physics. Neutron scattering, with its unique capability for studying the spin and charge ordering, has contributed significantly to our understanding of these materials.
Research Interests
Experimental condensed matter physics- Using neutron as a probe to study strongly correlated electron systems.
The microscopic origin of high-transition temperature (Tc) superconductivity, magnetism and electron-lattice coupling in high-Tc superconductors. Magnetism and lattice effects in colossal magnetoresistance (CMR) manganese oxides. Quantum criticality in Ru-based oxide materials and other transitional metal oxides. Our work is supported by the National Science Foundation and the Department of Energy.
Research Highlights
Magnon Damping by magnon-phonon coupling in Manganese Perovskites, P. Dai, H.Y. Hwang, J. Zhang, J. A. Fernendez-Baca, S-W. Cheong, C. Kloc, Y. Tomioka, and Y. Tokura, Phys. Rev. B 61, 9553 (2000).
One-dimensional nature of the magnetic fluctuations in YBa2Cu3O6.6, H. A. Mook, P. Dai, F. Dogan, and R. D. Hunt, Nature 404, 729 (2000).
Resonance as a measure of pairing correlations in the high-Tc superconductor YBa2Cu3O6.6, P. Dai, H. A. Mook, G. Aeppli, S. M. Hayden, and F. Dogan, Nature 406, 965 (2000).
Short-range polaron correlations in the ferromagnetic manganese oxides La1-xCaxMnO3, P. Dai, J. A. Fernandez-Baca, N. Wakabayashi, E. W. Plummer, Y. Tomioka, and Y. Tokura, Phys. Rev. Lett. 85, 2553 (2000).
Evolution of the resonance and incommensurate spin fluctuations in YBa2Cu3O6+x, P. Dai, H. A. Mook, R. D. Hunt, and F. Dogan, Phys. Rev. B 63, 054525 (2001).
Observation of magnetic moments in the superconducting state of YBa2Cu3O6.6, H. A. Mook, P. Dai, and F. Dogan, Phys. Rev. B 64, 012502 (2001).
Jahn-Teller Phonon Anomaly and Dynamic Phase Fluctuations in La0.7Ca0.3MnO3, Jiandi Zhang, P. Dai, J. A. Fernendez-Baca, E. W. Plummer, Y. Tomioka, and Y. Tokura, Phys. Rev. Lett. 86, 3823 (2001).
Polaron correlations in ferromagnetic CMR manganites, J. A. Fernandez-Baca, P. Dai, N. Wakabayashi, E. W. Plummer, S. Katano, Y. Tomioka, and Y. Tokura, J. Phys. Soc. Jpn. 70, 85 (2001).
Magnetic coupling in the insulating and metallic ferromagnetic La1-xCaxMnO3, P. Dai, J. A. Fernandez-Baca, E. W. Plummer, Y. Tomioka, and Y. Tokura, Phys. Rev. B 64, 224429 (2001).
Charge and Spin Structure in YBa2Cu3O6.35, H. A. Mook, P. Dai, F. Dogan, Phys. Rev. Lett. 88, 097004 (2002).
Microscopic spin interactions in colossal magnetoresistance manganites, J. A. Fernandez-Baca, P. Dai, H. Kawano, H. Yoshizawa, Y. Tomioka, and Y. Tokura, Phys. Rev. B 66, 054434 (2002).
Doping evolution of the phonon density of states and electron-lattice interaction in Nd2-xCexCuO4, H. J. Kang, P. Dai, D. Mandrus, R. Jin, H. A. Mook, D. T. Adroja, S. M. Bennington, S. H. Lee, and J. W. Lynn, Phys. Rev. B 66, 064506 (2002).
Educational Background
B.S. (1984), Department of Physics, Zhengzhou University, Henan, P. R. China Ph.D. (1993), Department of Physics and Astronomy, University of Missouri-Columbia
Professional Experience
| April 2001- | Associate Professor of Physics, The University of Tennessee, Collaborative Scientist, Oak Ridge National Laboratory |
| May 1999- March 2001 | Staff Member II, Solid State Division, ORNL |
| Dec., 1996-May 1999 | Staff Member I, Solid State Division, ORNL |
| Oct., 1993-Dec, 1996 | Postdoctoral Fellow, ORNL |
| Sep., 1993-Oct., 1993 | Postdoctoral Fellow, University of Missouri |