PSEUDOGAP: Megagauss fields probing the high Tc superconductor pseudogap
Research project selected under the 2016 call for proposals
Principal Investigator :
Cyril Proust ()
LNCMI (SCES)
Type of project : Disruptive Project
Date (start/end) : 2017 - 2019
Temperature-doping phase diagram of the cuprate high T c superconductors YBa 2 Cu 3 O y
Abstract
The origin of high-temperature superconductivity in copper-oxides is yet an unsolved problem in condensed matter physics. It is widely agreed that the main difficulty lies in the extremely complex nature of the pseudogap state. Indeed, the cuprate phase diagram seems to be organized around this mysterious phase characterized by a partial gap of the Fermi surface and other unusual electronic properties. In recent years, however, tremendous progress has been achieved owing to the recently developed capability of performing high-quality physical measurements in magnetic fields intense enough to suppress superconductivity: a series of discoveries, made at the French high-field lab [1-5], has led to establish that the pseudogap state i) corresponds to a radically different electronic state in which the carrier density at low doping is dictated by the number of doped holes, not by the number of holes predicted by band structure calculation [5], ii) supports Landau quasiparticles at low temperatures as in Fermi-liquid theory [1,6], iii) hosts a universal charge-density-wave (CDW) instability [3,4]. These discoveries have given an entirely new twist to the field.
Our project aims at exploring new directions opened by recent discoveries in the field of high T c cuprates. Namely, it is to address questions that are key to determine the mechanism of superconductivity: What is the nature of the pseudogap ground state? Is there any direct evidence of quantum criticality associated with the pseudogap? Our strategy is to use extremely intense magnetic fields to destroy superconductivity around optimal doping of YBCO, where T c and critical fields (H c2 ~150 T) are maximum and to study the superconducting-free ground state.
References:
[1]Doiron-Leyraud, N. et al . Nature 447 , 565 (2007).
- Cooper R. A. et al . Science 323 , 603 (2009).
[3]Wu, T. et al. , Nature 477 , 191 (2011).
[4]LeBoeuf D. et al. Nature Phys. 9 , 79 (2013).
[5]Badoux, S. et al. , Nature 531, 210 (2016).
[6] Rev. Condens. Matter Phys. 6 , 411 (2015).