Chemical potential oscillations from nodal Fermi surface pocket in the underdoped high-temperature superconductor YBa2Cu3O6+x

• Published in: Nature communications 2011-09, Vol.2 (1), p.471, Article 471
• Main Authors: Sebastian, Suchitra E., Harrison, N., Altarawneh, M.M., Liang, Ruixing, Bonn, D.A., Hardy, W.N., Lonzarich, G.G.
• Format: Article
• Language: English
• Subjects: 639/301/119/1003; Electrons; Experiments; Humanities and Social Sciences; Magnetic fields; multidisciplinary; Science; Science (multidisciplinary); Temperature
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms1468

The electronic structure of the normal state of the underdoped cuprates has thus far remained mysterious, with neither the momentum space location nor the charge carrier type of constituent small Fermi surface pockets being resolved. Whereas quantum oscillations have been interpreted in terms of a nodal-antinodal Fermi surface including electrons at the antinodes, photoemission indicates a solely nodal density-of-states at the Fermi level. Here we examine both these possibilities using extended quantum oscillation measurements. Second harmonic quantum oscillations in underdoped YBa 2 Cu 3 O 6+ x are shown to arise chiefly from oscillations in the chemical potential. We show from the relationship between the phase and amplitude of the second harmonic with that of the fundamental quantum oscillations that there exists a single carrier Fermi surface pocket, likely located at the nodal region of the Brillouin zone, with the observed multiple frequencies arising from warping, bilayer splitting and magnetic breakdown. It is unclear whether the Fermi surface in the normal state of underdoped cuprates is ambipolar or solely nodal. Here, measuring the second harmonic oscillations in underdoped YBa 2 Cu 3 O 6+x reveals the origin as an oscillatory chemical potential, based on which a Fermi surface consisting of a nodal pocket is identified.