Solid State Seminar
Wed, Aug 28
12:15 PM — 1:15 PM
Marshak Science160 Convent Ave.New York, NY 10031
Marshak Science, 418N
Solid State Seminar: Dr. Dragana PopovicSuperconductor-insulator transitions in underdoped La2-xSrxCuO4
National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA
The nature of the insulating ground state and the onset of superconductivity at low doping have been key issues in the physics of copper-oxide high-temperature superconductors (HTSC). In addition, the precise role of a magnetic field H in revealing the normal state of HTSC has not been well understood and remains a subject of debate. This talk will describe magnetoresistance measurements in underdoped La2-xSrxCuO4, a prototypical HTSC. They have been used to study (a) the emergence of superconductivity from the insulating state with doping, i.e. the doping-tuned superconductor-insulator transition (SIT), and (b) the suppression of superconductivity by a perpendicular H, i.e. the H-field-tuned SIT. The results are consistent with the picture of the doping-tuned SIT driven by phase fluctuations and localization of Cooper pairs by the competing charge order . The data also provide compelling evidence that the H-field-tuned SIT is not direct, and that quantum phase fluctuations dominate much of the relevant magnetic field regime . Similar effects may be expected in other hole-doped cuprates.
 X. Shi et al., Nature Materials 12, 47 (2013).  X. Shi et al., submitted (2013).