Quantum Phase Transition in the Normal State of High-Tc Cuprates at Optimum Doping

TL;DR

This study reveals a quantum phase transition in high-Tc cuprates at optimal doping, evidenced by a peak in the Hall number under high magnetic fields, indicating Fermi surface reconstruction and pseudogap collapse.

Contribution

It provides experimental evidence of a quantum phase transition at optimal doping in cuprates, linking Fermi surface changes to the pseudogap state.

Findings

Peak in Hall number at optimal doping under high magnetic field

Fermi surface reconstruction associated with quantum phase transition

Collapse of pseudogap coincides with Fermi surface change

Abstract

By using a 60 T magnetic field to suppress superconductivity in La2-pSrpCuO4, (LSCO) we reveal an anomalous peak in the Hall number, located at optimum doping and developing at temperatures below the zero-field superconducting transition temperature, Tc. The anomaly bears a striking resemblance to observations in Bi2Sr2-xLaxCuO6+delta (BSLCO) [F. F. Balakirev et al., Nature (London) 424, 912 (2003)], suggesting a normal state phenomenology common to the cuprates that underlies the high-temperature superconducting phase. The peak is ascribed to the transformation of the "Fermi arcs" into a conventional FS, the signature of a Fermi surface reconstruction associated with a quantum phase transition (QPT) near optimum doping and co-incident with the collapse of the pseudogap state.