Thermopower across the phase diagram of the cuprate <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>La</mml:mi><mml:mrow><mml:mn>1.6</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Nd</mml:mi><mml:mrow><mml:mn>0.4</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>Sr</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mi>CuO</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math>: Signatures of the pseudogap and charge density wave phases
Clément Collignon, Amirreza Ataei, Adrien Gourgout, S. Badoux, M. Lizaire, Anaëlle Legros, S. Licciardello, S. Wiedmann, Jiaqiang Yan, Jianshi Zhou, Qianli Ma, B. D. Gaulin, N. Doiron-Leyraud, Louis Taillefer
Abstract
Cuprate high-temperature superconductors universally exhibit a phase of charge order and a mysterious pseudogap phase. Using thermopower measurements, the authors explore here how the cuprate La${}_{1.6\ensuremath{-}x}$Nd${}_{0.4}$Sr${}_{x}$CuO${}_{4}$ (Nd-LSCO) evolves across these phases. They find that the thermopower displays a large increase below the pseudogap critical doping point ${p}^{*}$ and becomes negative in the charge order phase below that critical doping point ${p}_{\text{CDW}}$. This evolution hints at profound changes in the electronic structure at ${p}^{*}$ and ${p}_{\text{CDW}}$. They observe that these two critical dopings are well separated, implying that the two phases are clearly distinct.