Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session S30: Copper Oxide Superconductors: Charge and Spin Excitations |
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Sponsoring Units: DCMP Chair: Ricardo Lobo, ESPCI Paris Room: LACC 406B |
Thursday, March 8, 2018 11:15AM - 11:27AM |
S30.00001: Dependence of Tc on the q and w structure of the spin-fluctuation spectrum of YBCO6.6 Douglas Scalapino, Thomas Dahm A phenomenological spin-fuctuation analysis , based upon inelastic neutron scattering (INS) and angular resolved spectroscopy (ARPES) data for YBCO6.6(Tc =61K), is used to calculate the functional derivative of the d-wave eigenvalue of the linearized gap equation with respect to chi"(q,w)) at 70K. For temperatures near Tc, the variation of Tc with respect to chi"(q,w) is proportional to this functional derivative. Based on this, we discuss how different parts of the q and w spin-fuctuation spectrum of YBCO6.6 contribute to Tc. |
Thursday, March 8, 2018 11:27AM - 11:39AM |
S30.00002: Following spin fluctuations in La2-xSrxCuO4 across Tc and T* Yangmu Li, Ruidan Zhong, Genda Gu, John Tranquada, Igor Zaliznyak, Matthew Stone, Alexander Kolesnikov Understanding the evolution of magnetic correlations across the pseudogap as a function of temperature and chemical substitution in cuprates constitutes an important challenge. Inelastic neutron scattering is the natural technique for such studies, and recent improvements in capabilities allow for an enhanced ability to distinguish spin fluctuations from phonons. To this end, we have studied large single-crystal samples of La2-xSrxCuO4 with x=0.17 and 0.21, bracketing the critical concentration xc~0.19, on the time-of-flight spectrometer SEQUOIA at the SNS. Measurements were done in the rotating-crystal mode, providing four-dimensional data in the energy-momentum phase space, and at temperatures well below Tc, above Tc, and at 300 K. The results of a detailed analysis will be presented. |
Thursday, March 8, 2018 11:39AM - 11:51AM |
S30.00003: Anisotropic evolution of charge/spin excitations in square-planar cuprates Jonathan Pelliciari, Min Gu Kang, Yoshiharu Krockenberger, Daniel McNally, Eugenio Paris, Hideki Yamamoto, Thorsten Schmitt, Riccardo Comin Superconductivity is achieved in T'-Nd2CuO4 be means of oxygen annealing which injects electrons via controlled defect engineering. Here, we use Resonant Inelastic X-Ray Scattering (RIXS) to study the evolution of magnetic and charge excitations in parent and superconducting compounds. Our RIXS study reveals a hardening of the spin waves and the enhancement of charge excitations in the superconducting phase. Remarkably, the hardening of the low energy excitations is strongly anisotropic. A spectral weight redistribution between the antinodal and nodal directions is observed which brings important information on the dynamics of the superconducting state. The evolution of the low energy dynamics is then discussed in comparison with other cuprates as well as Fe-based superconductors. |
Thursday, March 8, 2018 11:51AM - 12:03PM |
S30.00004: Understanding spin excitations in cuprates by combining RIXS and numerical simulation Edwin Huang, Yingying Peng, Laura Chaix, Yao Wang, Chunjing Jia, Brian Moritz, Thorsten Schmitt, Zhi-Xun Shen, Lucio Braicovich, Giacomo Ghiringhelli, Wei-Sheng Lee, Thomas Devereaux The topic of spin excitations is central to the field of unconventional superconductivity. For the high-temperature cuprate superconductors, resonant inelastic X-ray scattering (RIXS) has emerged as a leading technique for probing spin excitations across much of the Brillouin zone. Here we present high-resolution RIXS spectra on two compounds, La2-xSrxCuO4 (LSCO) and (Bi,Pb)2(Sr,La)2CuO6+x (Bi2201), studying in detail the doping dependence of the spin excitations' dispersion, damping, and intensity in the underdoped region of LSCO and across the entire phase diagram of Bi2201. We show that the excitations' dispersion and redistribution of spectral weight upon doping are captured by the three-orbital Hubbard model, which we numerically simulate via determinantal quantum Monte Carlo. We further discuss the connection between charge transfer energy and compound-specific properties of spin excitations. The consistency between our model calculations and experimental data support a unified picture of spin excitations in the cuprates. |
Thursday, March 8, 2018 12:03PM - 12:15PM |
S30.00005: Neutron Scattering Study of Single Crystals of the High Tc Superconductor Nd-LSCO at High Doping Qianli Ma, Mirela Dragomir, Matthew Stone, Dalini Maharaj, Connor Buhariwalla, Hanna Dabkowska, Bruce Gaulin The La-214 family of cuprate superconductors is the original family of high temperature superconductors to be discovered. One branch of this family La(1.6-x)Nd(0.4)Sr(x)CuO4 (Nd-LSCO-x) has been of great interest as it displays the full complexity of the canonical hole-doped high TC phase diagram, but also displays well defined static charge and spin stripe order over a range of concentrations, optimized near x = 0.125. |
Thursday, March 8, 2018 12:15PM - 12:27PM |
S30.00006: 139La NMR Study of Charge and Spin Order in La1.885Sr0.115CuO4 Single Crystal Alexandre Arsenault, Sean Takahashi, Takashi Imai, Wei He, Young Lee, M. Fujita Recent technological advancements have made the detection of charge order in La2-xSrxCuO4 (x ~ 1/8) possible using x-ray diffraction nearly two decades after NMR measurements showed that the superconducting La2-xSrxCuO4 (x ~ 1/8) share nearly identical anomalies as Nd-codoped La1.48 Nd0.2Sr0.12CuO4 at the charge order transition of the latter. We revisit the elusive charge ordered state in La1.885Sr0.115CuO4 by measuring the 139La NMR linewidth and relaxation rate 1/T1. Our data demonstrates that the NMR linewidth broadens and 1/T1T is enhanced below the charge order temperature Tcharge = 80 K. In view of our recent finding that two different types of 63Cu NMR signals exist below Tcharge, we analyze 1/T1 using a two-component fit. We estimate the fractions of 139La nuclear spins with fast and slow 1/T1 components. The temperature dependence of slow 1/T1 exhibits qualitatively the same behavior as the optimally superconducting phase even below Tcharge down to Tc = 30K, but its volume fraction decreases with temperature. In contrast, 1/T1T of the fast component begins to increase immediately below Tcharge. We also show that the fast 1/T1 exhibits very strong magnetic field dependence below Tc. |
Thursday, March 8, 2018 12:27PM - 12:39PM |
S30.00007: Resolving the nature of electronic excitations in resonant inelastic X-ray scattering Riccardo Comin, Min Gu Kang, Jonathan Pelliciari, Jiarui Li, Thorsten Schmitt, Yoshiharu Krockenberger, Doug Bonn Resonant inelastic X-ray scattering (RIXS) has recently risen to becoming a versatile probe of elementary bosonic excitations in strongly correlated electron systems. However, various excitations with different charge, spin, and orbital nature are widely entangled in RIXS spectral axis, often complicating its interpretation. Here, we demonstrate a systematic method for the extraction of the character of excitations as imprinted in the azimuthal dependence of the RIXS signal. Using this novel approach, we resolve the charge, spin, and orbital nature of elastic scattering, (para-)magnon/bimagnon modes, and higher energy dd excitations in magnetically-ordered and superconducting copper-oxide perovskites (Nd2CuO4 and YBa2Cu3O6.75). In particular, we use the characteristic tensorial nature of each excitation to precisely and reliably disentangle the charge and spin contributions to the low energy RIXS spectrum. This procedure enables to separately track the evolution of spin and charge spectral distributions in cuprates with doping. Our results demonstrate a new capability that can be integrated into the RIXS toolset, and that promises to be widely applicable to materials with intertwined spin, orbital, and charge excitations. |
Thursday, March 8, 2018 12:39PM - 12:51PM |
S30.00008: CDW investigation of La2-xSrxCoO4 by soft x-ray scattering Claudio Mazzoli, Valentina Bisogni Recently, charge density wave (CDW) states have been proved to be practically ubiquitous in copper based high temperature superconductors (HTSCs). Questions on their nature and relation to superconductivity (SC) are considered crucial for understanding the pairing interaction at play in these unconventional materials. |
Thursday, March 8, 2018 12:51PM - 1:03PM |
S30.00009: An X-ray Scattering Study on CDW in Heavily Underdopded YBCO under High Magnetic Field Wei-Sheng Lee, Hoyoung Jang, Sanghoon Song, H. Huang, Y.-J. Liu, Satoshi Matsuzawa, H. Yasumura, Juan Porras, Matteo Minola, Bernhard Keimer, Jerome Hastings, Steven Kivelson, Zhi-Xun Shen, Thomas Devereaux, Chi-Chang Kao, H. Nojiri, D. L. Zhu, Jun-Sik Lee While the existence of charge density wave (CDW) in YBa2Cu3O6+x has now been firmly established, where in the phase diagram does it emerge remains an important question. X-ray scattering in the absence of magnetic field, as well as a lower field, suggests that the CDW becomes detectable for the hole concentration p > 0.08. However, these measurements are unlikely to represent the ground state properties because the superconductivity dominates at the low temperature, obscuring the development of the CDW. To resolve this limitation, we perform x-ray scattering at high magnetic field that is comparable to the upper critical field, using x-ray free electron laser with a pulsed magnet. The high magnetic field heavily suppresses YBCO’s superconductivity (SC) at the low temperature; so that we can investigate the existence of CDW at low temperature with minimal influence from the SC. The results and corresponding implications will be discussed in this talk. |
Thursday, March 8, 2018 1:03PM - 1:15PM |
S30.00010: Charge Excitations in Electron-Doped Cuprate Superconductors Matthias Hepting, Laura Chaix, Giacomo Ghiringhelli, Yingying Peng, Roberto Fumagalli, Lucio Braicovich, Brian Moritz, Edwin Huang, Kurt KUMMER, Nicholas Brookes, Wei-Cheng Lee, Tarapada Sarkar, Richard Greene, Zhi-Xun Shen, Thomas Devereaux, Wei-Sheng Lee The origin and universality of highly dispersive excitations near the zone center reported in the electron-doped cuprate Nd2-xCexCuO4 are still open questions. To tackle these questions, we have performed momentum-resolved resonant inelastic soft x-ray scattering (RIXS) experiments at the Cu L3-edge with ultrahigh energy resolution on another family of electron-doped compounds La2-xCexCuO4 (x=0.11, 0.15, and 0.18). Corresponding highly dispersive excitations are detected, indicating the universality of the feature in electron-doped cuprates. A polarization analysis of both incident and outgoing photons allows us to unambiguously unveil the charge nature of the excitations. Further, mapping out the dispersion of the excitation along the high-symmetry directions of reciprocal space reveals intriguing collective charge dynamics. |
Thursday, March 8, 2018 1:15PM - 1:27PM |
S30.00011: Effect of pressure on charge density wave order in the cuprate superconductor Nd-LSCO Amirreza Ataei, Adrien Gourgout, Sven Badoux, Francis Laliberté, Alizée Navarro, Nicolas Doiron-Leyraud, Louis Taillefer, Jianshi Zhou A phase of charge-density-wave (CDW) order is present in all hole-doped cuprates near a doping p = 0.12. As it competes with superconductivity, this CDW order causes a suppression of Tc near p = 0.12, visible as a dip in the Tc vs p dome of various cuprates. |
Thursday, March 8, 2018 1:27PM - 1:39PM |
S30.00012: Re-entrant charge order in overdoped (Bi,Pb)2.12Sr1.88CuO6+δ outside the pseudogap regime Yingying Peng, yingying peng, Roberto Fumagalli, Ying Ding, Matteo Minola, Sergio Caprara, Matthieu le Tacon, Xingjiang Zhou, Nicholas Brookes, Bernhard Keimer, Lucio Braicovich, Marco Grilli, Giacomo Ghiringhelli Charge modulations are considered as a leading competitor of high-temperature superconductivity in the underdoped cuprates, and their relationship to Fermi surface reconstructions and to the pseudogap state is an important subject of current research. Overdoped cuprates, on the other hand, are widely regarded as conventional Fermi liquids without collective electronic order. For the overdoped (Bi,Pb)2.12Sr1.88CuO6+δ (Bi2201) high-temperature superconductor, here we report resonant x-ray scattering measurements revealing incommensurate charge order reflections, with correlation lengths of 40-60 lattice units, that persist up to at least 250K. Charge order is markedly more robust in the overdoped than underdoped regime but the incommensurate wave vectors follow a common trend; moreover it coexists with a single, unreconstructed Fermi surface, without pseudogap or nesting features, as determined from angle-resolved photoemission spectroscopy. This re-entrant charge order is reproduced by model calculations that consider a strong van Hove singularity within a Fermi liquid framework. |
Thursday, March 8, 2018 1:39PM - 1:51PM |
S30.00013: Resonant Inelastic X-ray Scattering Study of Electronic Excitations in the Hole-doped Cuprates Biqiong Yu, Wojciech Tabis, Izabela Bialo, Flora Yakhou-Harris, Diego Casa, Kenji Ishii, Guichuan Yu, Martin Greven Resonant inelastic X-ray scattering (RIXS) enables the study of electronic excitations in strongly correlated materials with good momentum resolution and ever-improving energy resolution. Here we present our recent Cu K-edge and L-edge RIXS work for the hole-doped cuprates, with focus on the temperature dependence of charge-transfer excitations and dynamic charge-density-wave correlations. |
Thursday, March 8, 2018 1:51PM - 2:03PM |
S30.00014: Mechanism of superconductivity improvement under high-pressure: X-ray scattering study in YBCO Hai Huang, Hoyoung Jang, M. Fujita, Terukazu Nishizaki, Yu Lin, Jianlu Wang, Jianjun Ying, Jesse Smith, Curtis Kenney-Benson, Guoying Shen, Wendy Mao, Chi-Chang Kao, Yijin Liu, Jun-Sik Lee The record setting Tc of superconductor is achieved under high-pressure in hydrogen sulfide, which shows applying pressure is a powerful technic to enhance Tc. Great efforts have also been made to understand the pressure effect in YBa2Cu3O6+x. However, the underlying mechanism of superconductivity enhancement under pressure is still illusive. We measured different order structures in ortho-III YBa2Cu3O6.73 (YBCO) using the x-ray scattering as a function of pressure. We found that the pressure modifies the quenched disorder state in YBCO. This finding could explain changes in the order features such as oxygen order and charge-density-wave (CDW) under compression, as well as the improvement of Tc. More details will be introduced in the presentation. |
Thursday, March 8, 2018 2:03PM - 2:15PM |
S30.00015: Domain Evolution in Striped Phases of Cuprate Superconductors Yue Cao, Tadesse Assefa, Ross Harder, Wonsuk Cha, Genda Gu, John Tranquada, Kim Kisslinger, Ian Robinson Symmetry breaking and recovery in condensed matter systems are closely related to the exotic physical properties of these materials – superconductivity, magnetism, ferroelectricity, etc. A key signature of broken symmetry is the formation of structural domains, often on the nanometer size scale. Recent and upcoming implementations of coherent X-ray diffraction techniques can enable novel experimental opportunities to directly visualize the symmetry changes in quantum materials through the domain structure. |
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