3 Mar - 11.00 am | Fermi-surface reconstruction by charge order in cuprate superconductors
Location : Room Louis Weil - E424 (3rd floor, building E) - 25 rue des martyrs, 38000 Grenoble
Speaker : Louis TAILLEFER (University of Sherbrooke, Canada)
WARNING : due to the implementation of the advanced Vigipirate plan, if you do not hold a CNRS badge, please let us know that you’re coming at the latest 24 hours in advance,and we will add you to the list of authorized persons into CNRS campus.
Since the discovery of quantum oscillations in 2007, we know that the Fermi surface of the underdoped cuprate superconductor YBCO undergoes a reconstruction at low temperature. A signature of this reconstruction is the change of sign in the Hall and Seebeck coefficients, which become negative at low temperature. Observed in other hole-doped cuprates, this phenomenon is generic. By analogy with Eu-LSCO, where charge modulations are responsible for the reconstruction, a similar mechanism was inferred for YBCO . Charge modulations in YBCO have since been observed directly by NMR and X-ray diffraction. Charge order has also been observed in other materials – it represents a central new fact in the physics of cuprates.
We have used electrical, thermal and thermo-electric transport measurements in high magnetic fields to investigate the Fermi-surface reconstruction in YBCO and its impact on superconductivity. Based on our recent observation of a hole-like pocket in the Fermi surface of underdoped YBCO, I will argue that both charge order and the pseudogap play a role in the reconstruction. We have mapped out the upper critical field Hc2 as a function of doping across the phase diagram and find a dramatic drop in Hc2 below a critical doping p = 0.18. This shows that phase competition is what shapes the Tc dome in hole- doped cuprates.
- Download the abstract