Fermi-surface transformation across the pseudogap critical point of the cuprate superconductor La_(1.6−x)Nd_(0.4)Sr_xCuO_4

摘要

The electrical resistivity ρ and Hall coefficient RH 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 = 1 + 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.