High Tc cuprate superconductors: Ordering and quantum criticality

Room: DAV.0.23

Speaker: Prof. Anthony Carrington (University of Bristol)

https://www.bristol.ac.uk/people/person/Antony-Carrington-59a262f6-3e91-404b-b970-75741ff34290/

Title: High Tc cuprate superconductors: Ordering and quantum criticality

Abstract: I will discuss recent progress in understanding the normal state of cuprate high temperature superconductors. As doping is varied, cuprate superconductors display a variety of ordering tendencies, such as charge density waves (CDW) and a pseudogap in addition to the high temperature superconductivity.  Whether these competing orders enhance or decrease superconductivity remains a central question.  Here I will describe transport measurements (Hall effect, resistivity) at very high magnetic field and at high pressure and associated x-ray investigations which shed some light on this.  I will discuss the evidence for a quantum critical point associated with a change in Fermi surface volume evidenced by a rapid increase in the Hall carrier density.  Recently, we have discovered a CDW in the overdoped cuprate Tl₂Ba₂CuO_6+x (Tl-2201). I will show calculations which suggest that such CDWs could be responsible for several of the anomalous features observed in overdoped cuprates such as the above mentioned transition in the Fermi surface volume.