N. Doiron-Leyraud, S. Lepault, O. Cyr-Choiniere, B. Vignolle, F. Laliberte, J. Chang, N. Barisic, M. K. Chan, L. Ji, X. Zhao, Y. Li, M. Greven, C. Proust, L. Taillefer
The Hall coefficient R_H of underdoped HgBa2CuO4+d (Hg1201) was measured at low temperature in magnetic fields large enough to suppress superconductivity. The normal-state R_H(T) is found to drop with decreasing temperature and become negative below 10 K, as also observed in the orthorhombic bi-layer cuprate YBa2Cu3Oy (YBCO) at comparable doping. In YBCO, the negative R_H is the signature of a Fermi-surface reconstruction that produces a small electron pocket, attributed to the onset of charge-density wave order at low temperature. We infer that a similar Fermi-surface reconstruction occurs in the tetragonal single-layer material Hg1201. A striking similarity is also found in the normal-state Nernst coefficient, which drops below the pseudogap temperature T*, to reach a large negative value at low temperature, in both Hg1201 and YBCO. Our results offer compelling evidence that the mechanisms responsible for Fermi-surface reconstruction and pseudogap formation in hole-doped cuprates are universal.
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http://arxiv.org/abs/1210.8411
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