Hall, Seebeck, and Nernst Coefficients of Underdoped HgBa_{2}CuO_{4+δ}: Fermi-Surface Reconstruction in an Archetypal Cuprate Superconductor

Abstract

Charge-density-wave order has been observed in cuprate superconductors whose crystal structure breaks the square symmetry of the CuO_{2} planes, such as orthorhombic YBa_{2}Cu_{3}O_{y} (YBCO), but not so far in cuprates that preserve that symmetry, such as tetragonal HgBa_{2}CuO_{4+δ} (Hg1201). We have measured the Hall (R_{H}), Seebeck (S), and Nernst (ν) coefficients of underdoped Hg1201 in magnetic fields large enough to suppress superconductivity. The high-field R_{H}(T) and S(T) are found to drop with decreasing temperature and become negative, as also observed in YBCO at comparable doping. In YBCO, the negative R_{H} and S are signatures of a small electron pocket caused by Fermi-surface reconstruction, attributed to charge-density-wave modulations observed in the same range of doping and temperature. We deduce that a similar Fermi-surface reconstruction takes place in Hg1201, evidence that density-wave order exists in this material. A striking similarity is also found in the normal-state Nernst coefficient ν(T), further supporting this interpretation. Given the model nature of Hg1201, Fermi-surface reconstruction appears to be common to all hole-doped cuprates, suggesting that density-wave order is a fundamental property of these materials.