Seebeck coefficient of underdoped LSCO in high magnetic fields : Fermi-surface reconstruction by charge-density-wave order

The Seebeck coefficient $S$ of the hole-doped cuprate La$_{2-x}$Sr$_x$CuO$_4$~(LSCO) was measured in magnetic fields large enough to suppress superconductivity, for a range of Sr concentrations $x$ in the underdoped regime. For $x = 0.12$, 0.125 and 0.13, $S/T$ is seen to drop upon cooling and become negative at low temperature. The same behavior is observed in the Hall coefficient $R_{\rm H}(T)$. In analogy with other hole-doped cuprates at similar hole concentrations [1-4], the sign change in $S$ and $R_{\rm H}$ shows that the Fermi surface of LSCO undergoes a reconstruction caused by the onset of charge-density-wave modulations. Such modulations have indeed been detected in LSCO by X-ray diffraction in precisely the same doping range [5]. \\ {[1]} D.~LeBoeuf~{\it et al.}, Nature~{\bf 450},~533~(2007).\\ {[2]} D.~LeBoeuf ~{\it et al.}, Phys.~Rev.~B~{\bf 83},~054506~(2011).\\ {[3]} F.~Lalibert\’e~{\it et al.}, Nat.~Commun.~{\bf 2},~432~(2011).\\ {[4]} N.~Doiron-Leyraud~{\it et al.}, Phys.~Rev.~X~{\bf 3},~021019~(2013).\\ {[5]} T.~Croft~{\it et al.}, Phys.~Rev.~B~{\bf 89},~224513~(2014).\\