A quantum critical point at the heart of high temperature superconductivity
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Ramshaw, B., Sebastian, S., McDonald, R., Day, J., Tan, B., Zhu, Z., Betts, J., et al. (2015). A quantum critical point at the heart of high temperature superconductivity. Science, 348 (6232), 317-320. https://doi.org/10.1126/science.aaa4990
In the quest for superconductors with high transition temperatures (Tc s), one emerging motif is that unconventional superconductivity is enhanced by uc- tuations of a broken-symmetry phase near a quantum-critical point. While re- cent experiments have suggested the existence of the requisite broken symmetry phase in the high-Tc cuprates, the signature of quantum-critical uctuations in the electronic structure has thus far remained elusive, leaving their importance for high-Tc superconductivity in question. We use magnetic fields exceeding 90 tesla to access the underlying metallic state of the cuprate YBa2Cu3O6+δ over an unprecedented range of doping, and magnetic quantum oscillations reveal a strong enhancement in the quasiparticle effective mass toward optimal doping. This mass enhancement is a characteristic signature of quantum criticality, and identifies a quantum-critical point at Pcrit ≈ 0:18. This point also represents the juncture of the vanishing pseudogap energy scale and the disappearance of Kerr rotation, the negative Hall coefficient, and the recently observed charge order, suggesting a mechanism of high-Tc that is strongest when these definitive exper- imental signatures of the underdoped cuprates converge at a quantum critical point.
This work is supported by the US Department of Energy BES \Science at 100 T," the National Science Foundation, the State of Florida, the Natural Science and Engineering Research Council of Canada and the Canadian Institute for Advanced Research. S.E.S. ac- knowledges support from the Royal Society and the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013) / ERC Grant Agree- ment no. 337425.
European Research Council (337425)
External DOI: https://doi.org/10.1126/science.aaa4990
This record's URL: https://www.repository.cam.ac.uk/handle/1810/247749