An enduring theme in strongly correlated materials is the optimization of superconductivity in the vicinity of a quantum critical point. Quantum fluctuations are maximized at a quantum critical point, where an associated phase transition is suppressed to zero temperature. The occurrence of a quantum critical point in copper-oxide superconductors, however, has remained shrouded in uncertainty.
Our measurements over a wide range of dopings under very high magnetic fields in YbBa2Cu3O6+x uncovered two quantum critical points as a function of doping, each of which is in the vicinity of a maximum in superconducting temperature.
- Quasiparticle mass enhancement approaching optimal doping in a high-Tc superconductor
Science 348, 317 (2015)
B. J. Ramshaw, S. E. Sebastian, R. D. McDonald, James Day, B. S. Tan, Z. Zhu, J. B. Betts, Ruixing Liang, D. A. Bonn, W. N. Hardy, and N. Harrison
- Metal-insulator quantum critical point beneath the high Tc superconducting dome
Proceedings of the National Academy of Sciences 107, 6175 (2010)
Suchitra E. Sebastian, N. Harrison, M. M. Altarawneh, C. H. Mielke, Ruixing Liang, D. A. Bonn, W. N. Hardy, G. G. Lonzarich