Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session M52: ARPES in Copper-oxide Superconductors |
Hide Abstracts |
Sponsoring Units: DCMP Chair: Timir Datta, University of South Carolina Room: Mile High Ballroom 1F |
Wednesday, March 5, 2014 11:15AM - 11:27AM |
M52.00001: From insulator to d-wave superconductor: a persisting nodal gap and its interaction with superconductivity Yu He, Makoto Hishimoto, Inna Vishik, Ruihua He, Sung-Kwan Mo, Seiki Komiya, Yoichi Ando, Zhi-Xun Shen Gapless quasiparticle excitations along (pi,pi) direction in cuprate superconductors are enforced by sign-changing d-wave pairing symmetry. However, increasing number of evidences has been uncovered to support a finite gap along nodal direction in various families of underdoped cuprate superconductors. In this work, we will demonstrate with very comprehensive doping and temperature dependent nodal gap evolution in single layer LSCO system. The continuous doping evolution of the gap extending from insulating region of phase diagram all the way into superconducting dome indicates an origin other than d-wave superconductivity that interacts fundamentally with the superconducting order parameter. By lifting the symmetry-protected node, this gap coexists with superconductivity, meanwhile shows vivid interaction with superconductivity in low temperature underdoped region. [Preview Abstract] |
Wednesday, March 5, 2014 11:27AM - 11:39AM |
M52.00002: Angle resolved photoemission spectroscopy study of HgBa$_{2}$CuO$_{4+\delta}$ I.M. Vishik, N. Barisic, Y. Li, Guichuan Yu, Xudong Zhao, W.S. Lee, W. Meevasana, T.P. Devereaux, M. Greven, Z.-X. Shen HgBa$_{2}$CuO$_{4+\delta}$(Hg1201) is a model cuprate for scattering, optical, and transport experiments, but angle-resolved photoemission spectroscopy (ARPES) data are still lacking owing to the absence of a charge-neutral cleavage plane. We report on progress in achieving the optimal experimental conditions where quasiparticles can be observed in the near-nodal region. The superconducting gap, Fermi surface, and nodal kink were measured and quantified by ARPES for the first time in Hg1201, providing a crucial momentum space complement to other experimental probes. [Preview Abstract] |
Wednesday, March 5, 2014 11:39AM - 11:51AM |
M52.00003: Ultrafast Momentum-resolved Gap and Quasiparticle Dynamics in Bi2212 Christopher Smallwood, Wentao Zhang, Tristan Miller, Greg Affeldt, Chris Jozwiak, Hiroshi Eisaki, Ashvin Vishwanath, Dung-Hai Lee, Alessandra Lanzara Time- and angle-resolved photoemission spectroscopy (trARPES) is a direct and multifaceted probe of electron dynamics in crystalline solids. In cuprate high-temperature superconductors, it holds promise for understanding the interactions potentially linking superconductivity, charge density waves, and antiferromagnetism, which occur in close proximity in the cuprate phase diagram. We have used trARPES to measure the nonequilibrium gap and quasiparticle relaxation dynamics in Bi2212 while varying a range of dopings, temperatures, pump fluences, binding energies, and crystal momenta. Measurements reveal distinct signatures corresponding to superconducting and non-superconducting ordering tendencies, with potential indications of phase coexistence and/or competition. [Preview Abstract] |
Wednesday, March 5, 2014 11:51AM - 12:03PM |
M52.00004: Investigating the Effects of Doping Inhomogeneity on the ARPES Spectrum of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8}$ Stephen Parham, Haoxiang Li, Xiaoqing Zhou, Eduardo Calleja, Genda Gu, Kyle McElroy, Daniel Dessau Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8}$ (Bi2212) is a dirty material. This is readily seen with STM, which shows nanoscale variations in the gap parameter and local doping level. Through numerical simulation we investigate the effects of this doping inhomogeneity on the ARPES spectrum of Bi2212. We find that the main effect of the inhomogeneity is to broaden the spectrum in momentum, with an increasing magnitude towards the antinode. This has implications for the scattering rates extracted from MDC or EDC analysis. We show that after removing the doping inhomogeneity the scattering rate measured with ARPES qualitatively agrees with that from STM and Optical Reflectivity. [Preview Abstract] |
Wednesday, March 5, 2014 12:03PM - 12:15PM |
M52.00005: Zhang-Rice singlet hopping on bipartite tetragonal CuO L. Moreschini, S. Moser, H.-Y. Yang, D. Innocenti, F. Fuchs, N.H. Hansen, Y.J. Chang, K.S. Kim, A. Bostwick, E. Rotenberg, F. Mila, M. Grioni In the superconducting cuprates, corner sharing CuO$_4$ plaquettes host the formation and propagation of the Zhang-Rice singlet. Adding a further Cu atom to the center of such plaquettes results in a rare edge sharing geometry. The cupric oxide CuO indeed crystallizes in a lower-symmetry monoclinic form. At beamline 7.0.1 of the Advanced Light Source, we have grown tetragonal CuO thin films by pulsed laser deposition. By in situ angle-resolved photoemission (ARPES), we show that the first ionization state is a singlet propagating on two nearly independent corner sharing sublattices, and we resolve an inter-plaquette coupling of the order of 100 meV. [Preview Abstract] |
Wednesday, March 5, 2014 12:15PM - 12:27PM |
M52.00006: New Insights about the Strip Order in LBCO-1/8 by X-ray Natural Circular Dichroism Junfeng He, K. Sato, K. Tanaka, X.N. Sun, I. Kenji, S.I. Fujimori, F. Wilhelm, S. Motohiro, N. Kawamura, M. Fernandez, G. Gu, A. Rogalev, M. Fujita, Rui-Hua He Recent studies on LBCO-1/8 showed that the Kerr rotation of the infrared light polarization becomes non-zero below its charge stripe ordering temperature, and the sign of the Kerr rotation stays the same on opposite surfaces of the sample. This result has been interpreted as an evidence for a broken chiral symmetry of the stripe order. Such an interpretation is highly relevant to the nature of the broken symmetries that characterize the normal (pseudogap) state of cuprates as similar Kerr onsets have also been observed in several other cuprate families in the pseudogap state. Given its importance, insights from complementary experimental probes are required to shed new light on this issue. X-ray natural circular dichroism (XNCD), which measures circular dichroism in x-ray absorption, has been known as a useful probe for chirality of materials. Different from the Kerr effect, it is element-specific and predominantly measures a different part of the optical activity tensor that manifests a unique orientational dependence. We will present our first XNCD study of LBCO-1/8 as functions of the x-ray incident angle and temperature. A circular dichroic signal was observed within the stripe order state and shows a clear onset behavior. We will compare this result with the Kerr effect and neutron/x-ray diffraction results previously obtained on the same piece of sample. [Preview Abstract] |
Wednesday, March 5, 2014 12:27PM - 12:39PM |
M52.00007: Spin-charge interplay in antiferromagnetic LSCO studied by the muons, neutrons, and ARPES techniques Gil Drachuck, Elia Razzoli, Galina Bazalitski, Amit Kanigel, Christof Niedermayer, Ming Shi, Amit Keren We performed temperature dependent angle resolved photo emission spectroscopy (ARPES) measurements on an antiferromagnetic (AFM) LSCO sample with $x=1.92$\%. We find: quasiparticle peaks, Fermi surface, antinodal gap, and below $45$ K a nodal gap. Muon spin rotation measurements ensures that the sample is AFM and that the doping is close, but below, the spin glass phase boundary. In addition, we performed elastic neutron scattering measurements on the same sample, and determined the thermal evolution of the commensurate and incommensurate magnetic order. Our major finding is that nodal gap opens at a temperature well below the commensurate ordering at $140 $ K, and close to the incommensurate ordering temperature of $30$~K. [Preview Abstract] |
Wednesday, March 5, 2014 12:39PM - 12:51PM |
M52.00008: Accurate variational solution to describe a hole doped in a cuprate layer Hadi Ebrahimnejad, George Sawatzky, Mona Berciu Using a semi-analytical variational scheme, we study the spectral properties of a single hole doped in a CuO$_2$ plane, based on a model that includes the O 2p orbitals explicitly. We verify our choice of variational space by showing that its increase has little effect on the hole's dispersion. Our method predicts a hole dispersion that agrees very well with exact diagonalization results performed for 32-site clusters of the same model. This is quite remarkable given the much less computational effort required in our approach, which deals with an infinite lattice. We find that the low-energy states have considerable overlap with the Zhang-Rice singlet, however the overlap decreases for higher energy states, signalling the breakdown of the one-band effective treatment of this problem. Finally, we show that our results also explain the unusual drop in ARPES spectral weight observed experimentally to occur outside the magnetic Brillouin zone. [Preview Abstract] |
Wednesday, March 5, 2014 12:51PM - 1:03PM |
M52.00009: Quasiparticle lifetime in Optimally Doped Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ by Angle Resolved Photoemission Spectroscopy Daixiang Mou, Takeshi Kondo, Adam Kaminski Quasiparticle lifetime of optimally doped Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ has been systematically investigated by state-of-the-art angle resolved photoemission spectroscopy with energy, momentum and temperature resolution. In the normal state, Momentum Distribution Curve (MDC) width shows linear temperature dependence in all momentum and energy range, consistent with Marginal Fermi Liquid picture. In the superconducting state, the temperature dependent MDC width is strongly energy and momentum dependent. It shows a rapid drop below T$_C$. The drop is observed on the whole Fermi surface but more obvious in antinodal region. A sharp peak structure is revealed in energy dependent MDC width in antinodal region, which is a result of strong electron - boson mode coupling. The peak intensity has similar temperature dependence with spin resonance mode measured by neutron scattering. Detailed comparison between our ARPES results and theory calculation will be discussed. [Preview Abstract] |
Wednesday, March 5, 2014 1:03PM - 1:15PM |
M52.00010: Probing the temperature scales in cuprate high-temperature superconductor by ultrafast angle-resolved photoemission Wentao Zhang, Chris Smallwood, Tristan Miller, Chris Jozwaik, Hiroshi Eisaki, Dung-Hai Lee, Alessandra Lanzara We used time- and angle-resolved photoemission (trARPES) to measure the non-equilibrium electronic states of Bi$_2$Sr$_2$CaCu$_2$O$_8$ high temperature superconductor. Detailed temperature and pump fluence dependent measurements were taken on these samples to study the temperature scales in cuprate, giving a phase diagram from the view of the non-equilibrium study. These results indicate that trARPES is a powerful tool in probing the quantum phase transitions in materials. [Preview Abstract] |
Wednesday, March 5, 2014 1:15PM - 1:27PM |
M52.00011: ARPES study on annealing induced doping effects in electron doped cuprates Dongjoon Song, Yeongkwan Kim, Wonsig Jung, Yoonyoung Koh, Wonshik Kyung, Garam Han, Beomyoung Kim, H. Eisaki, Y. Yoshida, Seungryong Park, C. Kim In contrast to the hole doped cases, electron doped cuprates Ln$_{2-x}$Ce$_x$CuO$_{4-\delta}$, (Ln: rare earths) become superconducting after proper annealing which affects the oxygen content. Their normal state spin and charge dynamics also significantly depend on the heat treatment. While it is expected that oxygen deficiency and extra oxygen naturally induces electron and hole doping respectively, quantitative investigation has not been carried out so far. In this study, we prepared single crystalline samples of Pr$_{1-x}$LaCe$_x$CuO$_{4-\delta}$ (x=0.1, 0.18) and heat treated them under various conditions. We then performed ARPES and magnetic susceptibility measurements. It is found that the Fermi surface volume of the oxygen reduced x=0.1 system (T$_c$=25K) is comparable to that of the re-oxidized x=0.18 sample (T$_c$=19K), indicating that the electron carriers introduced by the Ce substitution is indeed compensated by the post-annealing (oxidation) process. Based on the results, we discuss the relationship between x, $\delta$ and T$_c$ of the electron doped cuprate superconductors in detail. [Preview Abstract] |
Wednesday, March 5, 2014 1:27PM - 1:39PM |
M52.00012: ABSTRACT WITHDRAWN |
Wednesday, March 5, 2014 1:39PM - 1:51PM |
M52.00013: A Revision of the Phase Diagram of Overdoped BSCCO Hongbo Yang, Genda Gu, Peter Johnson, Helmut Claus, David Hinks A re-examination of the temperature dependence of the anti-nodal gap observed in the overdoped region of the phase diagram BSCCO by angle-resolved photoemission spectroscopy (ARPES) suggests that the transition temperature, at which the gap, closes was under-estimated previously. In this study both oxygen and calcium doping were used as a means of achieving overdoping with both methods yielding similar results. Higher experimental resolution and new ways of data analysis improve the accuracy of extracting superconducting gap value. The present studies result in a modification to the accepted phase diagram. [Preview Abstract] |
Wednesday, March 5, 2014 1:51PM - 2:03PM |
M52.00014: A spectroscopic fingerprint of electron correlation in high temperature superconductors Gey-Hong Gweon, Kazue Matsuyama, G.-D. Gu, J. Schneeloch, R.D. Zhong, T.S. Liu The so-called ``strange metal phase'' of high temperature (high Tc) superconductors remains at the heart of the high Tc mystery. Better experimental data and insightful theoretical work would improve our understanding of this enigmatic phase. In particular, the recent advance in angle resolved photoelectron spectroscopy (ARPES), incorporating low photon energies ($\approx$ 7 eV), has given a much more refined view of the many body interaction in these materials. Here, we report a new ARPES feature of Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ that we demonstrate to have the key ability to distinguish between different classes of theories of the normal state. This feature--the anomaly in the nodal many body density of states (nMBDOS)--is clearly observed in the low energy ARPES data, but also observed in more conventional high energy ARPES data, when a sufficient temperature range is covered. We show that key characteristics of this anomaly are explained by a strong electron correlation model; the electron-hole asymmetry and the momentum dependent self energy emerge as key required ingredients. In particular, we find that, among many theories available for comparison, the phenomenological extremely correlated Fermi liquid (ECFL) model scores the best in terms of explaining the new anomaly feature. [Preview Abstract] |
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