Bulletin of the American Physical Society
2008 APS March Meeting
Volume 53, Number 2
Monday–Friday, March 10–14, 2008; New Orleans, Louisiana
Session L11: Superconductivity: Transport and Fermi Pockets |
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Sponsoring Units: DCMP Chair: Richard Greene, University of Maryland Room: Morial Convention Center RO9 |
Tuesday, March 11, 2008 2:30PM - 2:42PM |
L11.00001: Low Temperature Thermal Conductivity in Cuprate Superconductors Amidst Coexisting Charge Order: Part II - Effect of Self-Consistent Disorder and Vertex Corrections Philip Schiff, Adam Durst As in Part I, we consider a d-wave superconductor (dSC) in which the superconductivity coexists with charge density wave (CDW) order of wavevector ($\pi$,0). Here we discuss two significant improvements to the calculation of the low temperature thermal conductivity. First, rather than taking the 4-by-4 self-energy matrix to be a scalar and a constant, independent of the CDW order parameter, we compute it from an impurity density and scattering potential, within the self-consistent Born approximation. We find that self-consistency requires two off-diagonal terms in the self-energy matrix, in addition to the diagonal term. Furthermore, we find that these off-diagonal terms dominate in the clean limit. Second, we include ladder corrections to the bare vertex, as required to satisfy Ward identities. We compute their contribution, which is verified to be small in the low impurity density limit. However, the contribution of the off-diagonal terms in the self-energy matrix is found to be quite important, significantly reducing the critical value of the CDW order parameter beyond which the thermal conductivity vanishes. Results are used to identify signatures of the effect of charge order on low temperature thermal conductivity, with an eye toward understanding the effect of charge order on quasiparticle transport in the underdoped cuprates. [Preview Abstract] |
Tuesday, March 11, 2008 2:42PM - 2:54PM |
L11.00002: Low Temperature Thermal Conductivity in Cuprate Superconductors Amidst Coexisting Charge Order: Part I - Bare Bubble Calculation Adam Durst, Subir Sachdev We consider a d-wave superconductor (dSC) in which the superconductivity coexists with charge density wave (CDW) order of wavevector ($\pi$,0). While the nodes of the quasiparticle energy spectrum survive the onset of charge order, there exists a critical value of the CDW order parameter beyond which the quasiparticle spectrum becomes fully gapped. We perform a linear response Kubo formula calculation of thermal conductivity in the low temperature (universal) limit, where a simplified model of disorder has been employed and vertex corrections have been neglected. (Effects of self-consistent disorder and vertex corrections are discussed in a separate talk -- Part II.) Results reveal the dependence of thermal transport on increasing CDW order parameter up to the critical value at which the quasiparticle spectrum becomes fully gapped and thermal conductivity vanishes. In addition to numerical results, closed-form expressions are obtained in the clean limit for the special case of isotropic Dirac nodes. [Preview Abstract] |
Tuesday, March 11, 2008 2:54PM - 3:06PM |
L11.00003: Thermal and electrical transport in a random dissipative quantum system controlled by an infinite randomness critical point Adrian Del Maestro, Bernd Rosenow, Markus Mueller, Subir Sachdev The complicated interplay between quantum fluctuations and disorder in the vicinity of a quantum phase transition can have drastic effects and lead to exotic Griffiths phases and the flow to infinite randomness. We present a study of a dissipative Hertz-like theory in the presence of quenched disorder which may describe the quantum phase transition between a superconductor and metal in ultra narrow metallic wires tuned by an external source of pair-breaking. By finding a numerical solution to the large-N self-consistency equations for real-space chains we are able to directly compute the finite temperature thermal and electrical d.c. conductivities throughout the quantum critical regime. From an analysis of the typical and average correlation functions we find evidence for dynamically activated scaling in accord with recent strong disorder real space renormalization group calculations. [Preview Abstract] |
Tuesday, March 11, 2008 3:06PM - 3:18PM |
L11.00004: Theory of the Marginal Fermi liquid Arkady Shehter, Chandra Varma Marginal Fermi liquid is a successful phenomenological description of the strange metal phase of cuprates near optimal doping. We cast the theory into the standard microscopic form for interacting fermions, employing particle-hole rescattering and (singular) Landau parameters. We calculate the density-density correlation function and demonstrate its standard relation to the conductivity through the continuity equation. Internal consistency of the theory is ensured by showing that the relevant conservation laws are obeyed. The relation to the kinetic equation is established. [Preview Abstract] |
Tuesday, March 11, 2008 3:18PM - 3:30PM |
L11.00005: The effect of electron pockets on the quasiparticle interference patterns in cuprates Kangjun Seo, Jiangping Hu We study the hole/electron pockets in the $d$-density wave and the spin density wave states. While the hole/electron pockets can be seen in the presence of the DDW and the SDW orders, the shape, locations, and the number of the Fermi pockets are different, depending on the band structures and the wavevectors of the order parameters. We calculate the local density of states in the presence and the absence of the electron pockets in the DDW and SDW states. We find that the quasiparticle scattering interference patterns by the single impurity are dramatically affected in the presence of the DDW and SDW order in comparison with one without the electron pockets. [Preview Abstract] |
Tuesday, March 11, 2008 3:30PM - 3:42PM |
L11.00006: Quantum oscillations and Fermi surface in underdoped YBa$_2$Cu$_3$O$_{6.5}$ Nicolas Doiron-Leyraud, Cyril Proust, David LeBoeuf, Julien Levallois, Jean-Baptiste Bonnemaison, Ruixing Liang, Doug Bonn, Walter Hardy, Louis Taillefer We report quantum oscillations in the transport properties of YBa$_2$Cu$_3$O$_{6.5}$ at 10\% doping, showing that a well-defined Fermi surface with closed orbits is a fundamental property of underdoped cuprates. In contrast with the large Fermi surface seen on the overdoped side, we observe a very small orbit whose area is only 1.9\% of the Brillouin zone. Such a small Fermi surface does not come from the band structure of YBa$_2$Cu$_3$O$_{6.5}$ and is most likely the result of a reconstruction. [Preview Abstract] |
Tuesday, March 11, 2008 3:42PM - 3:54PM |
L11.00007: Shubnikov-de Haas oscillations in YBa$_2$Cu$_4$O$_8$ A. F. Bangura, J. D. Fletcher, A. Carrington, P. J. Heard, N.E. Hussey, J. Levallois, M. Nardonne, B. Vignolle, C. Proust, N. Doiron-Leyraud, D. LeBoeuf, L. Taillefer, S. Adachi The recent report of quantum oscillations in the single-chain underdoped cuprate YBa$_2$Cu$_3$O$_{6.5}$ - ortho II (hole doping p$\sim$0.10) points to the possibility that the underlying electronic structure in the underdoped region of the cuprate phase diagram contains Fermi surface pocket(s), at odds with results from ARPES experiments. In this talk I will describe our observation of quantum oscillations in the Hall resistivity $\rho_{xy}$ of the stoichiometric double-chain cuprate YBa$_2$Cu$_4$O$_8$ (hole doping p$\sim$0.14), in pulsed magnetic fields up to 62T. Our results show that both the area of the quasiparticle orbit and the cyclotron effective mass of YBa$_2$Cu$_4$O$_8$ are larger than those measured for YBa$_2$Cu$_3$O$_{6.5}$ - ortho II. The observed negative Hall coefficient and the failure of LDA bandstructure calculations to account for the oscillations suggests a non-trival origin. However, clear evidence of quantum oscillations in materials with such different levels of doping and the details of the transport properties of the two compounds, allows us to conclude that small Fermi surface pocket(s) are a generic feature of the underdoped side of the Yttrium-based cuprate phase diagram and are associated with the CuO$_2$ planes. [Preview Abstract] |
Tuesday, March 11, 2008 3:54PM - 4:06PM |
L11.00008: Electron pockets in the Fermi surface of hole-doped high-$T$c superconductors David LeBoeuf, Nicolas Doiron-Leyraud, Julien Levallois, Ramzy Daou, J.-B. Bonnemaison, Nigel Hussey, Luis Balicas, Brad Ramshaw, Ruixing Liang, Doug Bonn, Walter Hardy, S. Adachi, Cyril Proust, Louis Taillefer The Fermi surface of the electronic states in the underdoped `YBCO' materials YBa2Cu3Oy and YBa2Cu4O8 was recently shown to include small pockets, in contrast with the large cylinder that characterizes the overdoped regime, pointing to a topological change in the Fermi surface. Here we report the observation of a negative Hall resistance in the magnetic-field-induced normal state of YBa2Cu3Oy and YBa2Cu4O8, which reveals that these pockets are electron-like rather than hole-like. We propose that these electron pockets most probably arise from a reconstruction of the Fermi surface caused by the onset of a density-wave phase, as is thought to occur in the electron-doped copper oxides near the onset of antiferromagnetic order. [Preview Abstract] |
Tuesday, March 11, 2008 4:06PM - 4:18PM |
L11.00009: Evidence of Fermi surface reconstruction and the formation of small hole pockets in underdoped La$_{2-x}$Sr$_x$CuO$_4$: Far Infrared Hall measurements D.C. Schmadel, G.S. Jenkins, H.D. Drew, I. Tsukada, T. Ando The Hall Effect in La$_{2-x}$Sr$_x$CuO$_4$ films is measured from 3 to 100 meV as a function of temperature from 5K to 300K and carrier doping ranging from severely underdoped ($x=0.03$) to optimal doped ($x=0.15$). The behavior of the infrared Hall angle with temperature and frequency is found to be consistent with a simple extended Drude model at all dopings. A significant reduction of the Hall mass is observed when the hole doping level is reduced from optimal doping, which is consistent with a drastic reduction of the Fermi surface volume. These results are similar to earlier mid-IR Hall measurements obtained in underdoped YBCO, [1] and related to the recent observations of quantum oscillations reported in YBCO. [2] \newline \newline [1] L. B. Rigal, et al., Phys. Rev. Lett. 93, 137002 (2004). \newline [2] N. Doiron-Leyraud, et al., Nature, 447 565 (2007); A. F. Bangura, et al., Cond-mat/07074461 and E. A. Yelland, et al., Cond mat/07070057 [Preview Abstract] |
Tuesday, March 11, 2008 4:18PM - 4:30PM |
L11.00010: Evidence of Fermi surface reconstruction in Pr$_{2-x}$Ce$_x$CuO$_4$: Far IR Hall measurements in electron doped cuprates G.S. Jenkins, D.C. Schmadel, P. Bach, R.L. Greene, H.D. Drew The Hall Effect is measured at far infrared frequencies (24-85 1/cm) in Pr$_{2-x}$Ce$_x$CuO$_4$ films as a function of temperature from 5K to 300K and electron doping levels ranging from severely underdoped ($x=0.10$) to overdoped ($x=0.19$). In underdoped PCCO, the doping and temperature dependence of the complex Hall angle is found to be consistent with a simple Drude model with an associated reduction of the Hall mass in comparison with optimal doping. The mass reduction is consistent with Fermi surface reconstruction and the formation of small electron pockets. In overdoped PCCO, evidence for both electron and hole contributions to $\sigma_{xy}$ is observed even at low temperatures, a contradistinctive result compared with the DC Hall Effect in PCCO as well as the behavior observed in IR Hall measurements in La$_{2-x}$Sr$_x$CuO$_4$. These data suggest interactions through the exchange of incoherent zone corner magnons. [Preview Abstract] |
Tuesday, March 11, 2008 4:30PM - 4:42PM |
L11.00011: Disorder and the Metal-Insulator Crossover in Pr$_{2-x}$Ce$_x$CuO$_{4-y}$ P. L. Bach, W. Yu, J. S. Higgins, H. Xu, R. L. Greene, B. Weaver One of the outstanding issues in the electron doped cuprates is the role that oxygenation plays in the superconductivity and normal state properties. Oxygen addition can be considered both a doping and a disordering process. To disentangle these two effects, disorder can be introduced by irradiating the samples without altering doping. We report transport studies on optimal and underdoped Pr$_{2-x}$Ce$_x$CuO$_{4-y}$ films subject to proton irradiation and oxygenation. We establish a correlation between the static AFM and the metal-insulator crossover. Our separation of the disorder and doping effects also shed light on oxygen reduction effects in electron-doped cuprates. Supported by NSF grant DMR-0653535. [Preview Abstract] |
Tuesday, March 11, 2008 4:42PM - 4:54PM |
L11.00012: Doping dependence of the dynamic critical exponent in Pr$_{2-x}$Ce$_x$CuO$_4$ M.C. Sullivan, J. Sousa, M. Salvaggio, R.L. Greene Scaling analysis of voltage vs. current isotherms is a favorite tool to study the normal-superconducting phase transition in cuprate superconductors. This measurement has never been performed on the electron-doped cuprate superconductor Pr$_{2-x}$Ce$_x$CuO$_4$, despite unusual behaviors which may alter this phase transition and yield interesting results (behaviors such as the extended doping range of the anti-ferromagnetic phase and the quantum critical point). This is perhaps due to the lack of consensus regarding the analysis of voltage vs.\ current isotherms, due in part to finite-thickness effects even in thick ($d \approx 3000$\AA) films.\footnote{ Phys. Rev. B \textbf{69}, 214524 (2004)} If finite-thickness effects are taken into consideration, we can find the dynamic critical exponent $z$ in our Pr$_{2-x}$Ce$_x$CuO$_4$ films. We present our results of the dynamic critical scaling exponent $z$ as a function of doping. [Preview Abstract] |
Tuesday, March 11, 2008 4:54PM - 5:06PM |
L11.00013: Thermal and electrical transport in the cuprate superconductor Nd-LSCO Louis Taillefer, R. Daou, S.Y. Li, David LeBoeuf, Olivier Cyr-Choiniere, J.-Q. Yan, J.-S. Zhou, J.B. Goodenough We present a study of the thermal and electrical transport properties of the cuprate superconductor Nd-LSCO in a wide range of doping from x=0.12 to x=0.25. The behavior of the thermal conductivity in the zero temperature limit allows us to access the quasiparticle transport in both the superconducting and normal state. The impact of stripe order on quasiparticle transport is discussed. [Preview Abstract] |
Tuesday, March 11, 2008 5:06PM - 5:18PM |
L11.00014: Measurements of the Hall Effect and Resistivity in La$_{\rm 2-x}$Sr$_{\rm x}$CuO$_{\rm 4+\delta}$ with Ultrafine Stoichiometry Resolution, $\delta x$~$\sim$~2.5~$\times$~10$^{\rm -4}$ Jeffrey Clayhold, Bryan Kerns, Michael Schroer, David Rench, Gennady Logvenov, Anthony Bollinger, Ivan Bozovic Recent reports of sharp changes of transport properties with small variations of stoichiometry in cuprate superconductors have motivated us to look for similar behavior in optimally- and over-doped La$_{\rm 2-x}$Sr$_{\rm x}$CuO$_{\rm 4+\delta}$, using a recently completed system for creating and measuring samples with ultrafine stoichiometry resolution. The data are from MBE films grown with a linear stoichiometry gradient and were taken with a characterization system that can measure both the Hall effect and resistivity simultaneously at 31 different locations on the film. We will show new data for $x$ ranging from 0.15 to 0.30. [Preview Abstract] |
Tuesday, March 11, 2008 5:18PM - 5:30PM |
L11.00015: Magnetotransport and noise in lightly doped La$_{2-x}$Sr$_x$CuO$_4$ and La$_{2}$Cu$_{1-x}$Li$_{x}$O$_4$ Ivana Rai\v{c}evi\'{c}, Dragana Popovi\'{c}, Christos Panagopoulos, Takao Sasagawa We report a detailed comparative study of magnetotransport and noise in high quality single crystals of La$_{2-x}$Sr$_x$CuO$_4$ (LSCO) and La$_{2}$Cu$_{1-x}$Li$_{x}$O$_4$ ($x=0.03$) at temperatures 0.100$\leq T$(K)$\leq 150$ and fields $0\leq B$(T)$\leq 18$ parallel and perpendicular to the c-axis. Our results demonstrate that, in both materials at low $T$, the positive magnetoresistance (MR) exhibits signatures of glassiness, such as hysteretic behavior and memory. At such low $T\ll T_{sg} $ ($T_{sg}$ -- spin glass transition temperature) , the resistance noise data reveal other glassy features, such as slowing down of the charge dynamics and the onset of cooperativity as $T$ is reduced. The crossover to negative MR takes place at higher $T$ and $B$ in all samples and for both $B$ orientations. However, for $B\parallel c$, a steplike decrease in MR has been observed only in La$_{2}$Cu$_{1-x}$Li$_{x}$O$_4$ at high $T$, as the system enters the N\'{e}el state, similar to the result obtained on antiferromagnetic LSCO with $x=0.01$~[1]. *Supported by NSF No. DMR-0403491, NHMFL via NSF No. DMR-0084173, and The Royal Society.\\ \noindent [1] Y. Ando \textit{et al.}, Phys. Rev. Lett. \textbf{90}, 247003 (2003). [Preview Abstract] |
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