Effect of pressure on the pseudogap and charge density wave phases of the cuprate Nd-LSCO probed by thermopower measurements

We report thermopower measurements under hydrostatic pressure on the cuprate superconductor La$_{1.6-x}$Nd$_{0.4}$Sr$_x$CuO$_4$ (Nd-LSCO), at low-temperature in normal state accessed by suppressing superconductivity with a magnetic field up to $H = 31$ T. Using newly developed AC measurement technique suitable for high and field, we track evolution of Seebeck coefficient $S$. At ambient low temperature, $S/T$ was recently found suddenly increase Nd-LSCO pseudogap critical doping $p^{\star} 0.23$, consistent drop carrier density $n$ from $n 1 + p$ above $p^{\star}$ below. Under 2.0 GPa, observe that this jump is suppressed. This confirms previous study based electrical resistivity Hall effect which $dp^{\star}/dP \simeq - 0.01$ holes/GPa, thereby reinforcing interpretation driven pressure-induced shift van Hove point. It implies only exists when Fermi surface hole-like, puts strong constraints theories phase. also La$_{1.8-x}$Eu$_{0.2}$Sr$_x$CuO$_4$ charge density-wave phase near $p \sim 1/8$, reveals weakening pressure.