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Physics of strongly correlated electron systems.

Unexpected electronic and magnetic properties of this class of materials call for fundamental revisions of the theory of metals. Infrared and optical methods developed in my group are most informative in providing a detailed experimental picture of competing interactions in correlated electron systems. During the next several years we intend to focus on the studies of complex electrodynamics of this class of materials in high magnetic field. Currently this work is supported by the NSF and DOE.

Evolution of the optical conductivity across the phase diagram of high-Tc superconductors. From Padilla et al PRB72, 60511 (2005) link to paper 89

In a recent study we investigated the impact of high magnetic field on quasiparticle dynamics in heavy fermion system (in collaboration with S.V. Dordevic, K.S.D. Beach, N. Takeda, Y.J. Wang and M.B. Maple). We observed strong suppresion of the quasiparticle effective mass in magnetic fields as low as 17T. This effect is in quantitative agreement with the mean-field solution of the periodic Anderson model augmented with a Zeeman term.

The top panel presents the loss function for a heavy fermion system CeRu₄Sb₁₂ which has pronounced peaks at the frequencies of the longitudinal modes, such as the heavy plasmon. All field curvese are T=10 K . The middle panel shows the field dependence of quasiparticle effective mass m* extracted using different complimentary methods. The bottom panel schematically displays the periodic Anderson model (PAM) band structure, both in zero and high magnetic field. From link to pdf-92.

Recent publications:

D.N. Basov and T. Timusk, “Electrodynamics of high-Tc superconductors”, Reviews of Modern Physics 77, 721 (2005). PDF

Y. S. Lee, K. Segawa, Z. Q. Li, W. J. Padilla, M. Dummm, S. V. Dordevic, C. C. Homes, Y. Ando, and D. N. Basov, “Electrodynamics of the nodal metal state in weakly doped high- T_c cuprates” Phys. Rev. B 72, 054529 (2005) PDF

Y.-S. Lee, K. Segawa, Y. Ando, D. N. Basov, “Coherence and Superconductivity in Coupled One-Dimensional Chains: A Case Study of YBa₂Cu₃O_y”, Phys. Rev. Lett. 94, 137004 (2005) PDF

C. C. Homes, S. V. Dordevic, M. Strongin, D. A. Bonn, Ruixing Liang, W. N. Hardy, Seiki Koymia, Yoichi Ando, G. Yu, X. Zhao, M. Greven, D. N. Basov, and T.Timusk, “Universal scaling relation in high-temperature superconductors”, Nature 430, 539 (2004). PDF

S. V. Dordevic, K. S. D. Beach, N.Takeda, Y. J. Wang, M. B. Maple, and D. N. Basov “Heavy Fermion, Fluid in High Magnetic Fields: An Infrared Study of CeRu₄Sb₁₂” Physics Review Letters 96, 17403 (2006) PDF

S.Dordevic, Seiki Komiya, Yoichi Ando, and D.N. Basov, “Josephson Plasmon and Inhomogeneous Superconducting State in La2-xSrxCuO4” Physical Review Letters 91, 167401, (2003). PDF

M. Dumm, Seiki Komiya, Yoichi Ando, D.N. Basov, “Anisotropic Electromagnetic Response of Lightly Doped La2-x SrxCuO4 within the CuO2 Planes”, Physical Review Letters 91, 077004 (2003). PDF