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<b>Special CM/AMO Seminar</b><br>Optical Study of CuxTiSe2, Ba0.6K0.4Fe2As2 and High Field Torque Magnetometry Study on Several Iron-Based Superconductors<br><b>Gang Li (National High Magnetic Field Laboratory)</b>

Tuesday, April 24, 2012
12:00 AM
335 West Hall

Gang Li (National High Magnetic Field Laboratory)

CuxTiSe2 is an intercalated transition metal dichalcogenide system.The prototype TiSe2 undergoes a charge-density-wave(CDW) transition at about 200 K. By copper intercalation superconductivity was achieved in this octahedral structure TMDC for the first time in 2006, while the CDW order is gradually vanished. An optical study from x = 0 to 0.07 shows that TiSe2 is a semimetal both above and below the CDW transition temperature, which helps to clarify the CDW mechanism, and the doped superconducting compound is a peculiar low carrier density metal.

Optical measurement on single crystal sample of Ba0.6K0.4Fe2As2 identifies the pairing gap formation in optical conductivity spectrum with an s-wave line shape, and reveals by spectral weight analysis the fulfillment of the Ferrell-Glover-Tinkham sum rule at a low energy scale, which thus elucidating a difference between the Fe pnictide and high-Tc cuprate superconductors.

High magnetic field torque magnetometry measurements on iron-based superconductors in the aim of studying the dHvA effect and thus Fermiology of these materials are going on. Some preliminary data will be presented.