Thermopower across the pseudogap critical point of   La(1.6-x)Nd(0.4)Sr(x)CuO(4): Evidence for a quantum critical point in a   hole-doped high-Tc superconductor
  The thermopower S of the high-Tc superconductor La(1.6-x)Nd(0.4)Sr(x)CuO(4) was measured as a function of temperature T near its pseudogap critical point, the critical hole doping p* where the pseudogap temperature T* goes to zero. Just above p*, S/T varies as ln(1/T) over a decade of temperature. Below p*, S/T undergoes a large increase below T*. As with the temperature dependence of the resistivity, which is linear just above p* and undergoes a large upturn below T*, these are typical signatures of a quantum phase transition. This suggests that p* is a quantum critical point below which some order sets in, causing a reconstruction of the Fermi surface, whose fluctuations are presumably responsible for the linear-T resistivity and logarithmic thermopower. We discuss the possibility that this order is the "stripe" order known to exist in this material. 
R. Daou, Olivier Cyr-Choini\`ere, Francis Lalibert\'e, David LeBoeuf,   Nicolas Doiron-Leyraud, J.-Q. Yan, J.-S. Zhou, J.B. ...