Regensburg 2010 – wissenschaftliches Programm
TT 24.8: Vortrag
Mittwoch, 24. März 2010, 16:15–16:30, H19
Superconducting fluctuation regime in HgBa2CuO4+δ revealed by microwave measurements — •Neven Barišić1,3, Mihael S. Grbić2, Antonije Dulčić2, Yuan Li3, Xudong Zhao3, Guichuan Yu3, Martin Dressel1, Martin Greven3,4, and Miroslav Požek2 — 11. Physikalisches Institut, Universität Stuttgart, D-70550 Stuttgart, Germany — 2Department of Physics, Faculty of Science, University of Zagreb, P.O. Box 331, HR-10002 Zagreb, Croatia — 3Department of Physics, Stanford University, Stanford, California 94305, USA — 4School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
Superconducting (SC) fluctuations belong to fundamental properties of high-Tc superconductors. Although studied by various experimental techniques the highest temperature at which the superconducting fluctuations can be observed, is not yet unambiguously determined. Thus, an alternative experimental verification of the SC fluctuation regime is desirable. We are proposing a novel approach to microwave conductivity measurements to elucidate the phase diagram of high- Tc. Measurement are performed on a model high-Tc material: HgBa2CuO4+δ. From a set of the single c-axis data for a sample close to optimal doping we can clearly discern the opening of the pseudogap at T*=185 (15) K, the appearance of the superconducting fluctuations at a much lower temperature T’=105 (2) K, and the full transition to the superconducting state at the critical temperature Tc=94.3 K. Thus, with the presently acquired high sensitivity we establish that the superconducting fluctuations extend only to about 10 K above Tc.