The Optical Conductivity Group at the Light and Matter Laboratory
Highlights
January 2009 - New paper: Exchange boson dynamics in cuprates: Optical conductivity of HgBa2CuO4+δ, J. Yang, J. Hwang, E. Schachinger, J.P. Carbotte, R.P.S.M. Lobo, D. Colson, A. Forget, and T. Timusk, Phys. Rev. Letters 102, 027003 (4 pp.) (2009).
November 2008 - Visiting Scientist A. Pronin, Dresden High magnetic Field Lab., Germany - ESPCI Joliot Chair.
October 2008 - New paper: Multiple bosonic mode coupling in the charge dynamics of the electron-doped superconductor (Pr2-xCex)CuO4, E. Schachinger, C.C. Homes, R.P.S.M. Lobo, and J.P. Carbotte, Phys. Rev. B 78, 134522 (10 pp.) (2008).
September 2008 - New paper: Metallic Nature of Strained Single-Crystal La2/3Sr1/3MnO3 Films, A.M. Haghiri-Gosnet, M. Kouba, A.F. Santander-Syro, R.P.S.M. Lobo, P. Lecoeur, B. Mercey, Phys. Rev. B 78, 115118 (5 pp.) (2008).
July 2008 - Ludwig Genzel prize awarded to Ricardo Lobo - LEES 08 meeting, Vancouver, BC, Canada.
Our
general main interest is to measure the optical conductivity of strongly correlated electron
systems. These systems span a vast number of materials such as cuprate superconductors,
electrides (possibly), switchable mirrors, manganites and nickelates. We are also interested in the optical properties of non-equilibrium conventional superconductors.
Another reserach topic of major interest for us is the lattice dynamics and magneto-electric coupling in multiferroic compounds. These systems show simultaneous ferroelectric and ferromagnetic orders which can interact between themselves. Our research concentrates on the phonon infrared spectroscopy, which is sensitive to lattice displacements that induce the dielectric spontaneous polarization.
We also look into more conventional band filling metal-insulator transitions such as the one observed in reduced SrTiO3 and in transparent conducting oxides (TCOs).
The figure shown in this page illustrates the power of the optical conductivity in analyzing electronic correlation effects. The left panel shows what is expected for a metallic behavior: at low temperatures and energies a Drude peak smoothly develops. The right panel shows a dent in the previously smooth metallic behavior. This dent appears at temperatures below 100 K and is limited to enegies around 250 meV. It caracterizes the opening of a gap at the Fermi energy. Because the low frequency and low temperature Drude peak survives, this gap is open only at some portions of the Fermi surface. Click here to read more about this result.
To know in more detail about our research, take a look into our Research areas page.
