Bulletin of the American Physical Society
2005 APS March Meeting
Monday–Friday, March 21–25, 2005; Los Angeles, CA
Session Y13: Photoemission Studies of Superconductors |
Hide Abstracts |
Sponsoring Units: DCMP Chair: Daniel Dessau, University of Colorado Room: LACC 402B |
Friday, March 25, 2005 11:15AM - 11:27AM |
Y13.00001: Fine Details of the Electronic Excitations in the Near-Nodal Region of the Fermi Surface in Bi 2212 T. Valla, T.E. Kidd, J. Rameau, P.D. Johnson, G.D. Gu Recent high resolution ARPES experiments on high quality Bi$_2 $Sr$_2$CaCu$_2$O$_{8+\delta}$ samples have uncovered extremely coherent excitations in the near-nodal region of the Fermi surface. The width of these excitations at low energies and at low temperature seems to be essentially resolution limited. This observation has enabled a more detailed insight into the intrinsic properties of these excitations. Some of the ``fine features" that have not been previously resolved, will be discussed. This work was supported by the DOE under contract number DE- AC02-98CH10886. [Preview Abstract] |
Friday, March 25, 2005 11:27AM - 11:39AM |
Y13.00002: Doping dependence of the band structure of Bi2212 Adam Kaminski, Stephan Rosenkranz, Mike Norman, Helen Fretwell, Utpal Chaterjee, Juan Carlos Campuzano, Mohit Randeria, Helene Raffy, Z. Z. Lee, Kazuo Kadowaki We present careful study of doping dependence of the band structure of Bi2212 high temperature superconductor. Our study reveals many fine details that were not noticed before. We use this data to understand the spectrum of collective excitations present in this and other cuprate materials. [Preview Abstract] |
Friday, March 25, 2005 11:39AM - 11:51AM |
Y13.00003: Quasiparticle Dynamics of Bi$_2$Sr$_2$CaCu$_2$O$_8$ from High Momentum Resolution Laser-Based ARPES Jake Koralek, Fraser Douglas, Nick Plumb, Zhe Sun, Margaret Murnane, Henry Kapteyn, Steven Cundiff, Daniel Dessau, Y. Aiura, K. Oka, H. Eisaki We present the first laser based angle resolved photoemission (ARPES) study of the High Tc superconductor Bi-2Sr-2CaCu-2O-8. This new technique uses 6 eV photons from the 4th harmonic of a high repetition rate Ti:Sapphire oscillator. The new light source offers increased count rate and momentum resolution, while reducing surface sensitivity and background relative to traditional ARPES light sources. In addition to reproducing BSCCO features seen in previous ARPES experiments (d-wave superconducting gap, dispersion kinks, etc.) these improvements have allowed us to make much stronger statements about the nature of the quasiparticle dynamics both in the normal and superconducting states. [Preview Abstract] |
Friday, March 25, 2005 11:51AM - 12:03PM |
Y13.00004: Competing Degrees of Freedom in High Temperature Superconductor – New Insights from Angle Resolved Photoemission Spectroscopy G.-H. Gweon, S. Y. Zhou, J. Graf, M. C. Watson, T. Sasagawa, H. Takagi, D.-H. Lee, A. Lanzara A fundamental issue for the high temperature superconducting cuprates is how various degrees of freedom, e.g.~lattice and spin, compete or cooperate as basic ingredients of the superconductivity. In this talk, I will address this issue based on the line shape analysis of angle resolved photoemission data obtained on the optimally doped Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ high temperature superconductor. The momentum, energy, temperature and oxygen isotope mass dependence of the single particle spectral function will be analyzed. The important role of the lattice that we can learn primarily through the oxygen isotope mass dependence will be emphasized. [Preview Abstract] |
Friday, March 25, 2005 12:03PM - 12:15PM |
Y13.00005: Unusual spectral weight transfer in high temperature Bi-superconductors Jeff Graf, Gey-Hong Gweon, Shuyun Zhou, Eli Rotenberg, Hiroshi Eisaki, Alessandra Lanzara High resolution angle resolved photoemission spectroscopy (ARPES) studies of the electronic structure of single layer (Bi$_{2}$Sr$_{2}$CuO$_{6+\delta })$ and double layer (Bi$_{2}$Sr$_{2}$CaCuO$_{8+\delta })$ Bi-compound are reported. A detailed study of the quasiparticle spectral function as a function of momentum, temperature and doping is presented. Unusual spectral weight transfer is observed in both systems and discussed in terms of a strong interplay between the electron-lattice and electron-electron interaction in these materials. [Preview Abstract] |
Friday, March 25, 2005 12:15PM - 12:27PM |
Y13.00006: Doping Dependent Electronic Structure of KxC60 Monolayers Studied by Angle Resolved Photoemission W.L. Yang, V. Brouet, X.J. Zhou, Z. Hussain, Z.-X. Shen KxC60 (1$<$x$<$6) shows complicated but interesting phase transitions between insulators and metals, in contrast to a rigid band picture where the system always has a partially filled conduction band. The study on the novel doping behavior is thus of great interest but seriously intervened by lattice structure for bulk materials. Through angle resolved photoelectron spectroscopy, we were able to study systematically the electronic structure evolution of KxC60 monolayers which does not show bulk-like lattice structure change. Unexpectedly, our data strongly suggest the existence of phase separation between K3C60 and K4C60 in monolayers, accompanied by metal-insulator transition. We also reveal that the electron-phonon coupling manifests itself in different ways for the metallic and insulating phases. Further, the long standing problem on the shifting insulating peak with doping could be expected by a polaronic scenario for insulating phases. [Preview Abstract] |
Friday, March 25, 2005 12:27PM - 12:39PM |
Y13.00007: Evolution of Electronic Structure with Doping in (La$_{2-x}$Sr$_x$)CuO$_4$ X. J. Zhou, T. Yoshida, W. L. Yang, V. Brouet, Seiki Komiya, Yoichi Ando, F. Zhou, J. W. Xiong, W. X. Ti, Z. X. Zhao, T. Sasagawa, T. Kakishita, H. Eisaki, S. Uchida, A. Fujimori, Z. Hussain, Z.-X. Shen High resolution angle-resolved photoemission measurements have been carried out on (La$_{2-x}$Sr$_x$)CuO$_4$ (LSCO) over the entire doping range (x=0$\sim$0.3). Systematic evolution of the energy band, Fermi surface, and many-body effect with doping will be discussed. [Preview Abstract] |
Friday, March 25, 2005 12:39PM - 12:51PM |
Y13.00008: Evolution of the electronic structure from the insulator to the superconductor in Bi2212 cuprates Kiyohisa Tanaka, Teppei Yoshida, Kyle Michael Shen, Donghui Lu, Wei-Sheng Lee, Hajime Yagi, Atsushi Fujimori, Zhi-Xun Shen, . Risdiana, Takenori Fujii, Ichiro Terasaki We have performed angle-resolved photoemission study of Bi$_2 $Sr$_{2-x}$La$_x$CaCu$_2$O$_{8+\delta}$ (Bi2212) cuprates from the lightly-doped to the underdoped region, which can be achieved by a recent progress in sample synthesis. We found that the lower Hubbard band (LHB) of the parent insulator is gradually shifted upward with hole doping without changing the global dispersions, which indicates a shift of the chemical potential with hole doping. This behavior is analogous to that in Ca$_{2-x}$Na$_x$CuO$_2$Cl$_2$ (Na-CCOC) but is different from La$_{2-x}$Sr$_x$CuO$_4$ (LSCO), where the LHB stays well below the chemical potential and does not move in the underdoped region. The details of the electronic structure for different families of cuprates will also be compared from the viewpoint of doping dependence of the quasiparticle band and the $k_{F}$ position and the observed difference will be discussed. [Preview Abstract] |
Friday, March 25, 2005 12:51PM - 1:03PM |
Y13.00009: APRES study of the Bi$_2$Sr$_2$Ca$_2$Cu$_3$O$_{10}$ and HgBa$_2$CuO$_4$ Wei-Sheng Lee, Donghui Lu, Wanli Yang, Xingjiang Zhou, Kyle M. Shen, Guichuan Yu, Martin Greven, Chengtian Lin, Jun-ichi Shimoyama, Zhi-Xun Shen The wide variation of the critical temperature of the high Tc superconductors is an important unresolved issue. For example, the optimal Tc of the mercury-based superconductor is 97 K, while that of the lanthanum-based superconductor is only 38K. In this study, we used the Angle Resolved Photoemission Spectroscopy (ARPES) to explore the electronic state of the Bi2223 (Tc = 110K) and Hg1201 (Tc = 94K) system; both of them have a very high Tc compared to other high Tc superconductors. Comparisons of their electronic structures to other high Tc superconductors with lower critical temperature will discussed. [Preview Abstract] |
Friday, March 25, 2005 1:03PM - 1:15PM |
Y13.00010: ARPES study on four layered superconductor compound Ba2Ca3Cu4O8(O,F)2 (F0234) Yulin Chen, Wanli Yang, Xingjiang Zhou, Donghui Lu, Akira Iyo, Hiroshi Eisaki, Zahid Hussain, Zhixun Shen An interesting phenomenon found in several families of cuprate superconductors is that with the increase of the number of CuO$_{2}$ layers (that are believed to be responsible for the superconducting phenomenon) within a unit cell of the crystal, the T$_{c}$ increase first with the layer number n when n$<$=3, then decrease when n$>$3 and reach the maximum at n=3. To understand this, we use the Angular Resolved Photoemission Spectroscopy (ARPES) to study the four layered cuprate superconductor F0234 and compare the results with results from compounds with less layers. We found that the electronic band structure of the four layered system exhibits clear difference from the previously studied cuprate superconductors with less layers. These results provide new insights on the nature of cuprate physics. [Preview Abstract] |
Friday, March 25, 2005 1:15PM - 1:27PM |
Y13.00011: Bosonic Mode Coupling in the Single-Layer Bi-Cuprate, Bi2201 Worawat Meevasna, Nicholas Ingle, Xingjiang Zhou, Donghui Lu, Felix Baumberger, Wanli Yang, Kyle Shen, Wei-Sheng Lee, Juren Shi, Hiroshi Eisaki, Zhixun Shen In the study of the high-Tc superconductors, one of the recent highlights is the observation of the electron self-energy renormalization effect in the form of a ``kink'' in the dispersion. This kink is interpreted as the signature of a collective bosonic mode coupling to the electrons. In our study,high-resolution-angle-resolved-photoemission-spectroscopy data is collected with good statistics to reveal the fine structure in the electron self-energy of the single-layer Bi-cuprate, Pb0.55Bi1.5Sr1.6La0.4CuO6. The fine structure will be discussed. [Preview Abstract] |
Friday, March 25, 2005 1:27PM - 1:39PM |
Y13.00012: Elastic forward scattering in superconducting cuprates Lingyin Zhu, T. Dahm, Peter Hirschfeld, Douglas Scalapino We investigate the effect of elastic forward scattering on the ARPES spectrum of cuprates superconductors. The single particle elastic scattering rate at the antinodal point is shown to be suppressed upon the opening of the gap due to the cancellation between the normal and anomalous scattering processes, but is much larger at the nodal point. We further point out that the spectra for $\bf k$ points away from the Fermi level possess a dispersing quasiparticle peak and a rounded square root-like peak at the local gap edge ($\omega=\Delta_k$). While both of these features evolve with the concentrations and effective ranges of defects, the latter provides a possible direct measure of the superconducting order parameter away from the Fermi surface, and may thus be used to determine the range of the pair interaction. [Preview Abstract] |
Friday, March 25, 2005 1:39PM - 1:51PM |
Y13.00013: Low-lying excitations of a strongly correlated superconducting state: role of correlation in the ARPES experiments for cuprates Seiji Yunoki, Elbio Dagotto, Sandro Sorella Motivated by recent photoemission experiments on cuprates, the low-lying excitations of a strongly correlated superconducting state are studied numerically. It is observed that along the nodal direction these low-lying one-particle excitations show a linear momentum dependence for a wide range of excitation energies and, thus, they do not present a kink-like structure. The nodal Fermi velocity $v_{\rm F}$, as well as other observables, are systematically evaluated directly from the calculated dispersions, and they are found to compare well with experiments. It is argued that the parameter dependence of $v_{\rm F}$ is quantitatively explained by a simple picture of a renormalized Fermi velocity. The intimate correlation between quasi particle weight and the superconducting ordering is also discussed. [1] S. Yunoki, E. Dagotto, and S. Sorella, preprint (2004). [Preview Abstract] |
Friday, March 25, 2005 1:51PM - 2:03PM |
Y13.00014: On the band structure of bond-centered stripes Mats Granath We study the band structure of a stripe ordered system through mean-field treatments of both single and three band models for the Cu-O plane of the cuprate superconductors. The results suggest that the striking difference between low-energy nodal and anti-nodal excitations seen by ARPES [PRL 92, 187001 (2004)] in underdoped LSCO may be related to the parity of states living on bond-centered stripes and the corresponding coupling to the particular charge sensitive Cu-O bond-stretching phonon. [Preview Abstract] |
Friday, March 25, 2005 2:03PM - 2:15PM |
Y13.00015: ARPES in the cuprate superconductors -- a mean field study Tiago C. Ribeiro, Xiao-Gang Wen Angle resolved photo-emission spectroscopy (ARPES) experiments have played a key role in disclosing information about the cuprates. Intriguing features observed by ARPES in hole underdoped materials include the development of spectral weight inside the Mott gap, the nodal dispersion ``kink'' and the Fermi arcs. We show that a new mean field approach to the $tt't''J$ model, which describes doped Mott insulators in terms of hole-like quasiparticles and spin-charge separated excitations, provides a framework to account for the observed evolution of the electron spectral function from the undoped insulator to the overdoped Fermi metal. [Preview Abstract] |
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