Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session A41: Mainly Photoemission in High Tc Cuprates |
Hide Abstracts |
Sponsoring Units: DCMP Chair: Herbert Fotso, SUNY, Albany Room: 388 |
Monday, March 13, 2017 8:00AM - 8:12AM |
A41.00001: The electronic structure of Bi$_{\mathrm{2}}$Sr$_{\mathrm{2}}$CaCu$_{\mathrm{2}}$O$_{\mathrm{y}}$ in the presence of a super-current: Flux-flow, Doppler shift and quasiparticle pockets. Amit Kanigel, Muntaser Naamneh, J.C. Campuzano There are several ways to turn a superconductor into a normal conductor: increase the temperature, apply a high magnetic field, or run a large current. High-Tc cuprate superconductors are unusual in the sense that experiments suggest that destroying superconductivity by heating the sample to temperatures above Tc or by applying a high magnetic field result in different 'normal' states. Spectroscopic probes show that above Tc, in the pseudogap regime, the Fermi surface is partly gapped and there are no well-defined quasiparticles. Transport measurements, on the contrary, reveal quantum oscillations in high magnetic fields and at low temperatures, suggesting a more usual Fermi liquid state. Studying the electronic structure while suppressing superconductivity by using current, will hopefully shed new light on this problem. We performed angle-resolved photoemission experiments in thin films of Bi$_{\mathrm{2}}$Sr$_{\mathrm{2}}$CaCu$_{\mathrm{2}}$O$_{\mathrm{y\thinspace \thinspace }}$while running high-density current through the samples. Clear evidence was found for non-uniform flux flow, leaving most of the sample volume free of mobile vortices and dissipation. The super-current changes the electronic spectrum, creating quasiparticle and quasihole pockets. The size of these pockets as a function of the current is found to be doping dependent; it depends both on the superfluid stiffness and on the strength of interactions. [Preview Abstract] |
Monday, March 13, 2017 8:12AM - 8:24AM |
A41.00002: The overdoped region of the high Tc superconducting Bi2212 revisited N. Zaki, H-B. Yang, J. D. Rameau, P.D. Johnson, H. Claus, D.G. Hinks High-resolution angle-resolved photoemission (ARPES) is used to probe the temperature dependence of the gaps observed in the antinodal region of the Fermi surface (FS) in overdoped Bi2212. In particular we study samples with doping levels greater than 0.19, the latter having previously been determined to be the doping level associated with a Fermi surface reconstruction.[1-3] Careful simulation of the measured ARPES spectra indicates that any gap observed in this region of the FS at these doping levels is a reflection of the range of superconducting gaps associated with inhomogeneities observed in STM studies of the same systems. With this observation we are able to reexamine the phase diagram associated with the Bi2212 system and discuss the origin of the pseudogap associated with the underdoped region. [1] Yang et al., Phys. Rev. Lett. 107, 047003 (2011) [2] Fujita et al., Science 344, 612 (2014) [3] Badoux et al., Nature 531, 7593 (2016) [Preview Abstract] |
Monday, March 13, 2017 8:24AM - 8:36AM |
A41.00003: Temperature- and momentum-dependent self-energies of cuprate superconductors from ARPES Haoxiang Li, Xiaoqing Zhou, Stephen Parham, Theodore J. Reber, Jinsheng Wen, Zhijun Xu, Gerald Arnold, Genda Gu, Helmuth Berger, Daniel S. Dessau Electronic correlations, described by the “self-energy effects”, are understood to be the driving force for a great variety of the most exotic physics of modern materials, with these effects perhaps no more important than in the cuprate high temperature superconductors. Here, we use the latest ARPES data and analysis techniques to study how the self-energy effects of $Bi_2Sr_2CaCu_2O_{8+\delta}$ vary with momentum, temperature, and doping level, giving rich new information about the electronic interactions that drive the “strange-metal” normal state and the superconducting state of the cuprates. [Preview Abstract] |
Monday, March 13, 2017 8:36AM - 8:48AM |
A41.00004: Momentum-Resolved Thermodynamic: Key Effects of Self-Energies on the Entropy in Underdoped Cuprate Superconductors Xiaoqing Zhou, Haoxiang Li, Stephen Parham, Justin Waugh, Tom Nummy, Justin Griffith, james Schneeloch, Ruidan Zhong, Genda Gu, Gerald Arnold, Helmuth Berger, Daniel Dessau We demonstrate that the distribution of electronic entropy over momentum and energy space can be directly probed using Angle Resolved Photoemission Spectroscopy (ARPES). On slightly underdoped Bi$_{\mathrm{2}}$Sr$_{\mathrm{2}}$CaCu$_{\mathrm{2}}$O$_{\mathrm{8+\delta }}$, we investigated their detailed entropy evolutions as a function of momentum and temperature. We found our momentum resolved entropy to be qualitatively consistent with the bulk measurements, establishing ARPES as an alternative and complementary probe of thermodynamic properties to conventional methods. Furthermore, we reduce the entropy into temperature dependent density of states, and revisit the concepts of pseudogap and superconducting phase from a thermodynamic point-of-view. We conclude that the dynamics of self-energy is more relevant than the evolution of gaps in governing thermodynamic properties of cuprates. [Preview Abstract] |
Monday, March 13, 2017 8:48AM - 9:00AM |
A41.00005: Intertwined evolution of superconductivity and pseudogap in the presence of strong mode coupling Yu He, Makoto Hashimoto, Dongjoon Song, Sudi Chen, Junfeng He, Donghui Lu, Hiroshi Eisaki, Zhi-Xun Shen A commonly perceived salient feature of the otherwise extremely complex electronic phase diagram in cuprate high temperature ($T_c$) superconductors is the appearance of relatively simple superconductivity in the deeply overdoped regime. In a recent measurement of superfluid density only a small fraction of carriers are found to participate in the superconductivity in this region, violating a simple fermionic description. Here we report systematic angle-resolved photoemission spectroscopy (ARPES) study that provides a complementary fermionic perspective. Increasing the doping through a narrow range in the overdoped regime, the single particle spectrum divorces itself from a pseudogap-infected uncanonical behavior, characterized by a large gap-$T_c$ ratio and non-BCS temperature dependence, to the canonical \textit{d}-wave BCS superconducting gap over the entire Fermi surface. Accompanying this evolution, an electron-phonon coupling (EPC) feature, modified by the pseudogap, also abruptly disappears in an equally narrow doping range, suggesting its potential role as the superconductivity 'enhancer' near the optimal $T_c$. A combined perspective of the complementary bosonic and fermionic picture is needed to fully describe the phase diagram. [Preview Abstract] |
Monday, March 13, 2017 9:00AM - 9:12AM |
A41.00006: Laser-ARPES Study on Electron Scattering in Overdoped Bi2201 Superconductor Ying Ding, Lin Zhao, Li Yu, Cheng Hu, Xuan Sun, Jing Liu, Ping Ai, Guodong Liu, Chuangtian Chen, Zuyan Xu, Xingjiang Zhou We will present our high resolution angle-resolved photoemission (ARPES) measurements on heavily overdoped Bi$_{\mathrm{2}}$Sr$_{\mathrm{2}}$CuO$_{\mathrm{6}}$ superconductors. With substitution of lead (Pb) and high oxygen pressure annealing, overdoped and heavily overdoped Pb-doped Bi$_{\mathrm{2}}$Sr$_{\mathrm{2}}$CuO$_{\mathrm{6+}}$ (Pb-Bi2201) single crystals have been prepared. Laser-based ARPES measurements with high energy and momentum resolutions have been carried out to study the electron scattering rate as a function of momentum and temperature for Pb-Bi2201 with different doping levels. The implication of these results on understanding the anomalous normal state properties of the high temperature cuprate superconductors will be discussed. [Preview Abstract] |
Monday, March 13, 2017 9:12AM - 9:24AM |
A41.00007: Standing-wave photoemission study of the high-Tc superconductor Bi2Sr2CaCu2O8$+$d Cheng-Tai Kuo, Shih-Chieh Lin, Giuseppina Conti, Shu-Ting Pi, Luca Moreschini, Aaron Bostwick, Julia Meyer-Ilse, Eric Gullikson, Jeffrey Kortright, Tien-Lin Lee, Slavomir Nemsak, Andres F. Santander-Syro, Ivan A. Vartaniants, Warren Pickett, Charles S. Fadley It is believed that the key element of superconductivity in the high-Tc cuprates is the electron- or hole- doping of the CuO2 planes within their layered structures with large c-axis lattice parameters. An important challenge remaining is the unambiguous differentiation of the electronic structure of these CuO2 layers and those of the intermediate layers. Conventional angle-resolved photoemission spectroscopy (ARPES) with energies of 6 to 150 eV has provided much information, but collects photoelectrons from only the topmost surface layers rather than the full unit cell for the typical cuprate Bi2Sr2CaCu2O8$+$d (Bi-2212) Here we present a soft x-ray standing-wave photoemission study of Bi-2212, providing depth resolution of the different atomic planes (CuO2, Ca, SrO, and BiO). Rocking curves of core-level and valence spectra were used to derive layer-resolved densities of states (DOSs) within Bi-2212. DFT calculations incorporating the Bi-2212 supermodulation structures are compared to the layer-specific DOSs. Our work thus supplies new insights into the electronic structure of the cuprates. [Preview Abstract] |
Monday, March 13, 2017 9:24AM - 9:36AM |
A41.00008: Determining the depth distribution of RIXS excitations through standing-wave excitation S. C. Lin, C.-T Kuo, G. Ghiringhelli, Y. Y. Ping, G. De Luca, D. Di Castro, N. Brookes, M. Huijben, L. Moreschini, A. Bostwick, J. Kortright, J. Meyer-Ilse, E. Gullikson, A. Taleb-Ibrahimi, J. Rault, S.-H. Yang, L. Braicovich, C. Fadley The interface properties of oxide heterostructures exhibit novel physical effects that are due to the coupling of the charge, spin and orbital states. Resonant inelastic x-ray scattering (RIXS) is a powerful technique for studying in an element- and orbital specific way for charge transfer, $d$-$d$, magnetic, and other excitations, but it lacks depth resolution. Here we combine soft x-ray RIXS at the Cu L3 resonance with SW excitation to provide depth resolution and interface sensitivity, with first application to superconductor/half-metallic ferromagnetic multilayers of (La$_{1.85}$Sr$_{0.15}$CuO$_{4})_{n}$/(La$_{0.66}$Sr$_{0.33}$MnO$_{3})_{m}$ (LSCO/LSMO). The standing wave was swept along the direction normal to the sample surface by varying the incidence angle around the multilayer Bragg angle, producing ``rocking curves'' (RCs) of the intensities of individual excitations. The RCs of RIXS excitations are significantly different for samples grown on SrO- and TiO$_{2}$- terminated SrTiO$_{3}$, indicating different depth distributions. For the dd excitations of the TiO$_{2}$-terminated sample, the z$^{2}$ orbital excitations arise from the interface, while the xy and xz/yz orbital excitations arise from the bulk region of the LSCO layer. [Preview Abstract] |
Monday, March 13, 2017 9:36AM - 9:48AM |
A41.00009: Laser-ARPES Study on Superconducting gap, Pseudogap and Quasiparticle scattering rate of Bi2201 Superconductors Xuan Sun, Cheng Hu, Ying Ding, Yingying Peng, Li Yu, Lin Zhao, Guodong Liu, Chuangtian Chen, Zuyan Xu, Xingjiang Zhou The nature of the anomalou normal state properties has been a long-standing puzzle in high temperature cuprate superconductors. Here we will present our laser-based angle-resolved photoemission spectroscopy (ARPES) results on underdoped and optimallydoped Bi2(Sr,La)2CuO6 Bi2201) superconductor. Taking advantage of the high resolution of Laser-ARPES, we have carried out systematic investigation on the superconducting gap, pseudogap, and scattering rate as a function of momentum and temperature for La-Bi2201 for Bi2201 samples with different doping levels. The implications of these results on the understanding of the normalstate will be discussed [Preview Abstract] |
Monday, March 13, 2017 9:48AM - 10:00AM |
A41.00010: Competing electronic orders within a multi-band reconstructed Fermi surface in the layered cuprate superconductor Pr$_2$CuO$_4$ Nicholas Breznay, Ian Hayes, Sylvia Lewin, Alex Frano, Toni Helm, James Analytis, Yoshiharu Krockenberger, Hideki Yamamoto, Zengwei Zhu, Kimberly Modic, Ross McDonald The reconciliation of quantum oscillation, ARPES, and resonant x-ray scattering experiments provides a unique opportunity to understand competing electronic orders in the cuprates. In particular, the Fermi surface (FS) evolution with carrier doping, and the relevance of competing electronic orders (such as charge order), remain topics of active debate. In T' structure, electron-doped compounds such as Pr$_2$CuO$_4$, recent quantum oscillation measurements show evidence for a reconstructed FS near maximal T$_c$. However, discrepancies with ARPES measurements and the ($\pi, \pi$) reconstruction scenario - such as the absence of an electron pocket - still remain. In this talk I will describe recent high-field transport and resonant x-ray scattering studies on superconducting Pr$_2$CuO$_4$. We find evidence for weak, nearly temperature-independent charge order, along with a high-field Hall effect that indicates a reconstructed, multi-band Fermi surface. This developing picture illustrates a crucial link between non-superconducting electronic orders in the electron-doped cuprates. [Preview Abstract] |
Monday, March 13, 2017 10:00AM - 10:12AM |
A41.00011: Polaron-plasmon Superconductivity in Strontium Titanate Alexander Edelman, Peter Littlewood Strontium titanate is a bulk insulator that becomes superconducting at remarkably low carrier densities. Even more enigmatic properties become apparent at the strontium titanate/lanthanum aluminate (STO/LAO) interface and it is important to disentangle the effects of reduced dimensionality from the poorly-understood pairing mechanism. Recent experiments measuring the surface photoemission spectrum\footnote{Z. Wang et al, Nat. Mater. (2016)} and bulk tunneling spectrum\footnote{G. Swartz et al, arXiv:1608.05621} have found a cross-over, as a function of carrier density, from a polaronic regime with substantial spectral weight associated with strongly coupled phonons, to a more conventional weakly coupled Fermi liquid. Interestingly, it is only the polaronic state that becomes superconducting at low temperatures, although the properties of the superconducting phase itself appear entirely conventional. We interpret these results in a simple analytical model that extends an Engelsberg-Schrieffer theory of electrons coupled to a single longitudinal optic phonon mode to include the response of the electron liquid, and in particular phonon-plasmon hybridization. We perform a Migdal-Eliashberg calculation within our model to obtain this material's unusual superconducting phase diagram. [Preview Abstract] |
Monday, March 13, 2017 10:12AM - 10:24AM |
A41.00012: A ferroelectric quantum phase transition inside a superconducting dome Willem Rischau, Xiao Lin, Christoph P. Grams, Dennis Finck, Steffen Harms, Johannes Engelmayer, Thomas Lorenz, Yann Gallais, Benoît Fauqué, Joachim Hemberger, Kamran Behnia SrTiO$_{3}$, a quantum paraelectric, becomes a metal with a superconducting instability after removal of an extremely small number of oxygen atoms. It turns into a ferroelectric upon substitution of a tiny fraction of strontium atoms with calcium. The exceptionally dilute superconductor and ferroelectric are both percolative orders, which may be accidental neighbors or intimately connected, as in the picture of quantum critical ferroelectricity. We find that in Sr$_{1-x}$Ca$_{x}$TiO$_{3-\delta}$ ($0.002 |
Monday, March 13, 2017 10:24AM - 10:36AM |
A41.00013: Polaronic behavior in a weak-coupling superconductor Adrian Swartz, Hisashi Inoue, Tyler Merz, Yasuyuki Hikita, Srinivas Raghu, Tom Devereaux, Steven Johnston, Harold Hwang Superconductivity in the dilute semiconductor SrTiO$_{\mathrm{3}}$ has remained an open question for more than 50 years. The extremely low carrier densities at which superconductivity occurs suggests an unconventional origin of superconductivity beyond the adiabatic limit in which the Bardeen-Cooper-Schrieffer (BCS) and Migdal-Eliashberg theories are based. Using a newly developed method for engineering band alignments at oxide interfaces, we have measured the doping evolution of the dimensionless $e$-ph coupling strength ($\lambda )$ and superconducting gap in Nb-doped SrTiO$_{\mathrm{3}}$ by high resolution tunneling spectroscopy. In the normal state, we observe density of states replicas remarkably similar to observations from photoemission experiments. The observation of multi-phonon processes indicates strong polaronic coupling ($\lambda \approx $1) to the highest energy longitudinal optical phonon mode. Surprisingly, when cooled below the superconducting transition temperature, we observe a single superconducting gap corresponding to weak-coupling BCS theory, indicating an order of magnitude smaller pairing strength ($\lambda _{\mathrm{BCS}}\approx $0.1). These results indicate that SrTiO$_{\mathrm{3}}$ occupies a highly unusual regime of polaronic superconductivity, ideal for probing anti-adiabatic superconductivity. [Preview Abstract] |
Monday, March 13, 2017 10:36AM - 10:48AM |
A41.00014: Abstract Withdrawn |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700