Fermi-surface transformation across the pseudogap critical point of the cuprate superconductor La_(1.6-x) Nd_(0.4)Sr_x CUO_4

摘要

The electrical resistivity p and Hall coefficient R_h of the tetragonal single-layer cuprate La_(1.6-x)Nd_(0.4)Sr_xCuO_4 were measured in magnetic fields up to H = 37.5 T, large enough to access the normal state at T →0, for closely spaced dopings p across the pseudogap critical point at p~* = 0.23. Below p~*, both coefficients exhibit an upturn at low temperature, which gets more pronounced with decreasing p. Taken together, these upturns show that the normal-state carrier density n at T = 0 drops upon entering the pseudogap phase. Quantitatively, it goes from n = l + p at p = 0.24 to n = p at p = 0.20. By contrast, the mobility does not change appreciably, as revealed by the magnetoresistance. Our data are in excellent agreement with recent high-field data on YBa_2Cu_3O_y, and La_(2-x)Sr_xCuO_4. The quantitative consistency across three different cuprates shows that a drop in carrier density from 1 + p to p is a universal signature of the pseudogap transition at T = 0. We discuss the implication of these findings for the nature of the pseudogap phase.