Hall, Seebeck, and Nernst Coefficients of Underdoped HgBa2CuO4+d: Fermi-Surface Reconstruction in an Archetypal Cuprate Superconductor

TL;DR

This study measures Hall, Seebeck, and Nernst coefficients in underdoped HgBa2CuO4+d, revealing Fermi-surface reconstruction similar to other cuprates, indicating density-wave order is a fundamental property of hole-doped cuprates.

Contribution

It provides evidence of Fermi-surface reconstruction in tetragonal Hg1201, a cuprate that preserves square symmetry, expanding understanding of density-wave order in cuprates.

Findings

Negative Hall and Seebeck coefficients at low temperatures suggest electron pockets.

Fermi-surface reconstruction is observed in Hg1201, similar to YBCO.

Normal-state Nernst coefficient supports the presence of density-wave order.

Abstract

Charge density-wave order has been observed in cuprate superconductors whose crystal structure breaks the square symmetry of the CuO2 planes, such as orthorhombic YBa2Cu3Oy (YBCO), but not so far in cuprates that preserve that symmetry, such as tetragonal HgBa2CuO4+d (Hg1201). We have measured the Hall (R_H), Seebeck (S), and Nernst 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, 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.