Bulletin of the American Physical Society
2009 APS March Meeting
Volume 54, Number 1
Monday–Friday, March 16–20, 2009; Pittsburgh, Pennsylvania
Session B2: HTSC: Fermi Pockets and Quantum Oscillations |
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Sponsoring Units: DCMP Chair: Robert Laughlin, Stanford University Room: Spirit of Pittsburgh Ballroom BC |
Monday, March 16, 2009 11:15AM - 11:51AM |
B2.00001: Competing order, Fermi surface reconstruction, and quantum oscillations in high temperature superconductors Invited Speaker: Recent quantum oscillation measurements in underdoped high temperature superconductors in high magnetic fields and low temperatures have ushered in a new era. These experiments appear to explore the normal state from which superconductivity arises and provide evidence of a reconstructed Fermi surface consisting of electron and hole pockets in a regime in which such a possibility was previously considered to be remote. Here we explain the observations with the theory that the alleged normal state exhibits a hidden order, the $d$-density wave. The success of our analysis underscores the importance of spontaneous breaking of symmetries, Fermi surface reconstruction, and quasiparticles. We primarily focus on the version of the order that is commensurate with the underlying crystalline lattice, but also touch upon the consequence of incommensuration. In addition, the effect of possible bilayer splitting and the nature of quantum oscillations in the mixed state are addressed. [Preview Abstract] |
Monday, March 16, 2009 11:51AM - 12:27PM |
B2.00002: Quantum Oscillations in underdoped YBCO: the nature of Fermi surface reconstruction and evolution toward the Mott insulating regime Invited Speaker: I will present results of quantum oscillation measurements we have measured in underdoped YBCO$_{6+x}$ that reveal a small Fermi surface. Results of angular dependent measurements enable us to obtain clues as to the nature of order that reconstructs the Fermi surface. I will also present results of doping-dependent measurements that enable us to trace Fermi surface evolution as the insulating regime is approached. \vspace{4 mm} Work was performed in collaboration with N. Harrison, G. G. Lonzarich, C. Mielke, R. Liang, D. Bonn and W. Hardy [Preview Abstract] |
Monday, March 16, 2009 12:27PM - 1:03PM |
B2.00003: Fermi Arcs or Fermi Pockets Invited Speaker: In the pseudogap phase of the cuprate superconductors, a significant portion of the Fermi surface is still gapped at temperatures above the transition temperature Tc. Instead of a closed Fermi surface, the low-energy electronic excitations appear to form unconnected Fermi arcs separated by gapped regions. It is generally assumed that the spectral function is particle-hole symmetric (at low energies) in both regions - with a peak at the Fermi level on the Fermi arcs centered around the nodes and a local minimum at the Fermi level in the gapped regions away from the arcs. Using high resolution angle-resolved photoemission and new methods of analysis, we show that on a sizable portion of the Fermi surface, including the Fermi arcs, the electronic structure in the immediate vicinity of the Fermi level is not particle-hole symmetric in the pseudogap phase. This is clear evidence that superconducting pairing does not originate from the Fermi arcs. The observations are also consistent with the possibility that the Fermi arcs are in fact the inner surface of the predicted Fermi pockets. This work was carried out in collaboration with Hongbo Yang, Jon Rameau, Tonica Valla, Alexei Tsvelik and Genda Gu and was supported by the Department of Energy. [Preview Abstract] |
Monday, March 16, 2009 1:03PM - 1:39PM |
B2.00004: Field-Induced Quantum Critical Route to a Fermi Liquid in Overdoped Tl$_2$Ba$_2$CuO$_{6+x}$ Invited Speaker: In high temperature superconductivity, charge doping is a natural tuning parameter that takes copper oxides from the antiferromagnet through the superconducting `dome'-shaped region. In the metallic state above $T_{\rm c}$ the standard Landau's Fermi-liquid theory of metals, as typified by the temperature squared ($AT^2$) dependence of resistivity, appears to break down. The expected recovery of the usual Fermi-liquid metal on the high doping side is fundamental but ill understood. Here we uncover a new transformation in an overdoped superconducting copper oxide Tl$_2$Ba$_2$CuO$_{6+x}$ from the non-Fermi to a Fermi-liquid state driven by magnetic field [1]. From the $c$-axis resistivity measured up to 45~T, we show that the Fermi-liquid $AT^2$ features, accompanied by a field-linear magnetoresistance, appear above a field $H_{\rm FL}$. This crossover field $H_{\rm FL}$ decreases linearly with decreasing temperature $T$ and lands at a quantum critical point (QCP) near the upper critical field $H_{\rm c2}(0)$. The Fermi-liquid coefficient $A(H)$ shows a power-law diverging behavior on the approach to the QCP, indicating the second-order quantum phase transition at this field. The connection between the field-induced QCP and the pseudogap observed in the underdoped regime will be discussed. \\ \\ \noindent [1] T. Shibauchi {\it et al.}, Proc. Natl. Acad. Sci. USA {\bf 105}, 7120 (2008). [Preview Abstract] |
Monday, March 16, 2009 1:39PM - 2:15PM |
B2.00005: Fermi surface reconstruction in high-$T_{c}$ superconductors Invited Speaker: The recent observation of quantum oscillations in underdoped high-$T_{c}$ superconductors (1), combined with their negative Hall coefficient at low temperature (2), reveals that the Fermi surface of hole-doped cuprates includes a small electron pocket. This strongly suggests that the large hole Fermi surface characteristic of the overdoped regime undergoes a reconstruction caused by the onset of some order which breaks translational symmetry. Here we consider the possibility that this order is ``stripe'' order, a form of combined charge / spin modulation observed most clearly in materials like Eu- doped and Nd-doped LSCO. In these materials, the onset of stripe order coincides with major changes in transport properties (3), providing strong evidence that stripe order is indeed the cause of Fermi-surface reconstruction. We identify the critical doping where this reconstruction occurs and show that the temperature dependence of transport coefficients at that doping is typical of metals at a quantum critical point (4). We discuss an interpretation of the pseudogap as a fluctuating precursor of the stripe-ordered phase.\\ \\ This work was performed in collaboration with L. Balicas, D.A. Bonn, J. Chang, O. Cyr-Choini\`{e}re, R. Daou, N. Doiron- Leyraud, W.N. Hardy, N.E. Hussey, F. Lalibert\'{e}, D. LeBoeuf, S.Y. Li, R. Liang, C. Proust, H. Takagi, and J.S. Zhou.\\ \\ (1) N. Doiron-Leyraud \textit{et al}., Nature \textbf{447}, 565 (2007).\\ (2) D. LeBoeuf \textit{et al}., Nature \textbf{450}, 533 (2007).\\ (3) R. Daou \textit{et al}., Nature Physics, in press (DOI 10.1038/nphys1109); http://arXiv.org/abs/0806.2881.\\ (4) R. Daou \textit{et al}., to be published; http://arXiv.org/abs/0810.4280. [Preview Abstract] |
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