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Seminar:Magnetic oscillations in cuprate superconductors: measures of Fermi surface reconstruction or interlayer coupling?


Timothy Ziman

Institut Laue Langevin and LPMMC, CNRS Grenoble, France


Time: 15:00-16:00pm, Tuesday, January 23, 2018

Location: Room 242, East 4, Zijingang campus, Zhejiang University

 

Abstract

The magnetic oscillations in bilayer high-temperature superconductors have been widely studied over the last decade and consist of three equidistant low frequencies with a central frequency several times more intense than its two shoulders. This remains a puzzle in spite of numerous attempts to explain the corresponding small Fermi-surface pockets. Furthermore the ARPES data indicate only four Fermi-arcs with bilayer splitting, and show no sign of such small areas in the Fermi surface. Here we argue that the magnetic oscillations,in particular in YBa2Cu3O6, provide a measure of the interplanar electronic coupling rather than the areas of fine-grain reconstruction of the Fermi surfaces coming from induced charge density waves. This identification is based on the relative intensities of the different peaks, as well as their angular dependence, which points to an effective Fermi surface that is larger than the oscillation frequencies, and is compatible with several indications from ARPES. The dominance of such frequencies with respect to the fundamental frequencies from the Fermi surface is natural for a strongly correlated quasi-two dimensional electronic systems where non-linear mixings of frequencies are more resistant to sample inhomogeneity.

 

This work is in collaboration with Pavel Grigoriev (Landau Institute, Moscow)

 

 

About the Speaker

Undergraduate, Auckland New Zealand (1971-1974)

Doctorate at Oxford with Roger Elliott (1975-1978)

Postdoc at Cornell (LASSP) (1979-1981); Scientist at Institut Laue Langevin, Grenoble (1981-1985);Senior postdoc at Rutgers (with Elihu Abrahams) (1985-1988)

Assistant professor at University of Delaware (1988-1993);

Director de Recherche au CNRS in France (1993-).

Director of the Theory Group of the Institut Laue Langevin (2011-)