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

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.