In the thermopower of underdoped cuprates (Vol. 44 No. 4)

Comparison of calculated (line) and measured (symbols) thermopower of Bi2Sr2CuO6+d. The undulations (arrowed) arise from electron-like Fermi-surface pockets.

In recent years the possibility of electron-like Fermi-surface pockets in the high-Tc cuprates has become an area of intense experimental and theoretical interest. What is the origin of these pockets? Are they connected to the mysterious pseudogap, a depletion in the density of states that dominates thermodynamic and transport properties over a wide range of temperature and doping? Until now, experimental support for these pockets has been confined to samples which, in addition to pseudogap effects, exhibit a separate spin/charge stripe correlation, making their connection to the pseudogap unclear.

In the present paper we calculate the thermopower of high-Tc cuprates from the resonating-valence-bond spin-liquid model developed by Yang, Rice and Zhang, achieving an excellent match with experimental data. A key result of this work is the identification of features in the observed thermopower corresponding to electron pockets in the Fermi-surface appearing with the opening of the pseudogap. These results link the pseudogap with Fermi-surface reconstruction and will be of considerable interest to researchers using photoemission, quantum oscillations and other techniques presently engaged in efforts to detect these pockets directly.

J. G. Storey, J. L. Tallon and G. V. M. Williams, ‘Electron pockets and pseudogap asymmetry observed in the thermopower of underdoped cuprates’, EPL, 102 (2013) 37006