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Calendar: ALS Calendar
Title: Arkady Shekhter, April 8 290K Seminar Speaker at UC Berkeley
When: 04/ 8/2013 2:30 PM - 3:30 PM
Description: SPEAKER: Dr. Arkady Shekhter, Los Alamos
TITLE: Ultrasonic Signatures at the Superconducting and Pseudogap Phase Boundaries in Cuprate High Temperature Superconductors
ABSTRACT: (below)
DATE & TIME: Monday, April 8, 2013, 2:30 pm
PLACE: 3 Le Conte, UC Berkeley

Also, please sign up for an individual meeting with Dr. Jarillo-Herrero on Monday April 8 (at or by emailing Elaine, cc'd here).

Available times to meet with Dr.Arkady Shekhter (in 575 Birge Hall for individual meetings) are:


Title: Ultrasonic Signatures at the Superconducting and Pseudogap Phase Boundaries in Cuprate High Temperature Superconductors (A Line of Phase Transitions Terminating in a Quantum Critical Point Inside the Superconducting Dome)
Authors: Arkady Shekhter,1 and B. J. Ramshaw,1 Fedor F. Balakirev,1Ross D. McDonald,1 Jon B. Betts,1 and Albert Migliori1 Ruixing Liang,2 W. N. Hardy,2 D. A. Bonn,2 1Pulsed Field Facility, NHMFL, Los Alamos National Laboratory, Los Alamos, NM 87545 2University of British Columbia, Vancouver, Canada
Abstract: Superconductivity in cuprates exists over a broad range of chemical compositions and hole and electron dopings. Before we can identify the mechanism for superconducting pairing in these materials we have to understand the metallic state from which superconductivity emerges. The character of anomalous metallic behavior close to optimal doping where superconductivity is strongest, so called “strange metal”, suggests that fluctuations associated with a quantum critical point might be at play. This scenario requires that a line of classical phase transitions for which the quantum critical point is an end point at zero temperature. Whether pseudogap boundary in temperature-doping phase diagram of cuprates is just such a line of classical phase transition has been a subject of great controversy. Resonant study of elastic response of the single-crystal YBCO cuprates produces a thermodynamic signature of a line of phase transitions that terminates in a quantum critical point at zero temperature inside the superconducting dome. In the underdoped YBCO this line is coincident with the onset of magnetic order at the pseudogap boundary as detected by polarized neutron scattering. Our measurement extends this phase boundary to near-optimal doping where it is found below the superconducting transition. These findings provide a compelling evidence for the quantum critical origin of the anomalous metallic state in cuprates and the mechanism of high temperature superconductivity.
Location: 3 Le Conte, UC Berkeley