Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session F08: Superconductivity: Copper Oxide - Spectroscopy |
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Sponsoring Units: DCMP Chair: Ricardo Lobo, ESPCI ParisTech Room: BCEC 150 |
Tuesday, March 5, 2019 11:15AM - 11:27AM |
F08.00001: Terahertz spectroscopy of the cuprate superconductor La2-xSrxCuO4 in the photoexcited nonequilibrium state Hiroaki Niwa, Naotaka Yoshikawa, Dongjoon Song, Hiroshi Eisaki, Ryo Shimano
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Tuesday, March 5, 2019 11:27AM - 11:39AM |
F08.00002: C-Axis Spectra of La2-x BaxCuO4 in the Normal and Superconducting State Vladimir Martinez, Luyi Yan, David Tanner, Genda Gu Reflectance spectra of superconducting La2-xBaxCuO4 have been studied for polarization parallel to the c-axis in a wide frequency range from 20-35,000 cm-1, at doping from 0≤x≤0.155 and temperatures above and below Tc. The samples are single crystals grown using the traveling solvent floating zone method. These samples were wet polished with alumina fine powder to make a good reflective surface. The c-axis spectra showed insulating behavior, with only lattice vibrations below the charge-transfer gap. We observed below Tc no evidence for a Josephson plasma edge in the far infrared, despite seeing good superconducting behavior for the a-axis spectra. The results of annealing in an oxygen atmosphere will be discussed. |
Tuesday, March 5, 2019 11:39AM - 11:51AM |
F08.00003: Intrinsic electronic Raman spectrum and pairing symmetry in cuprate superconductors Hyun-Tak Kim Since the polarized electronic Raman scattering (ERS) measures the characteristics of the bulk rather than the surface, ERS data generate more accurate information. An ERS theory1) is that, when dx2-y2-wave symmetry is assumed, I(ω) ≈ω, linear behaviour in the B2g mode and II(ω) ≈ω3 for the B1g mode were calculated below an energy gap. ERS experiments1,2) showed the linear behaviour in the B2g mode of the node area below Tc for underdoped cuprate crystals. This is evidence of d-wave symmetry. However, since the measured data in inhomogeneous crystals with at least two phases has an averaged effect of the two phases to the measurement region, the measured data should be decomposed to analyze the intrinsic property. The ERS data well decomposed in an electron-doped cuprate Pr2-xCexCuO4-δ2) allow us to demonstrate the intrinsic effect. Here, we show the intrinsic nonlinear Raman spectrum obtained by subtracting the pseudogap characteristic of a nonlinear from the linear Raman spectrum measured in the B2g mode of the node area below Tc. The intrinsic nonlinear behaviour implies the existence of the nodal superconducting gap denying d-wave pairing symmetry. 1) PRL 72, 396 (1994). 2) PRB 72, 214510 (2005). |
Tuesday, March 5, 2019 11:51AM - 12:03PM |
F08.00004: Photoinduced phase transitions in cuprate superconductors: ordering vs. doping effects Ralph El Hage, Victor Rouco, Anke Sander, Fabian Cuellar, David Sanchez Manzano, Jacobo Santamaria, Javier Villegas Complex oxides posses an extremely rich phase diagram, in which the transitions between different ground states are triggered by small changes of the carrier density or by disorder. Interestingly, the interplay between these two mechanisms –and the resulting phase– can be externally manipulated by illumination. Despite the amount of work performed on cuprate superconductors, a clear picture of the mechanisms governing photo-induced effects has not emerged. In particular, whether doping or ordering effects are dominant has not been settled. Here we investigate that through light illumination effects in oxygen deficient YBa2Cu3O7-x thin films in which different degrees of disorder are induced through i) changes in the growth conditions (“quenching”) and ii) ion irradiation. Generally, light induces an increase in the superconducting critical temperature and in the carrier density coupled to a decrease in the normal state resistivity. However differences in the response of quenched and irradiated samples have been observed, which suggests that light-induced ordering may play an important role in the photoinduced effects. |
Tuesday, March 5, 2019 12:03PM - 12:15PM |
F08.00005: Infrared linear dichroism resonance in over-, under-, and optimally-doped cuprate superconductors Jungryeol Seo, Alok Mukherjee, Mumtaz Murat Arik, Deepu George, Andrea Markelz, John Cerne, Chao Zhang, Hao Zhang, John Y.T. Wei, Peter Armitage, Gad koren, Tal Kirzhner We report systematic measurements on epitaxial thin films of high-temperature cuprate superconductors using polarization sensitive measurements. We measure the complex Faraday angle at zero magnetic field as a function of temperature (10-300K), energy (3 to 2330 meV), and doping. We observe a Faraday rotation signal, which shows sample orientation dependence that can be best associated with linear dichroism (LD) [1]. The LD signal may be due to nematic charge ordering in the cuprates, as has been observed in dc Hall transport measurements [2]. The Faraday rotation signal, as large as 22 mrad near 400 meV, is strongest in under-doped films even at 300K and it shows strong frequency dependence as well as doping dependence, which provides important clues for resolving the microscopic mechanism responsible for the anisotropy. |
Tuesday, March 5, 2019 12:15PM - 12:27PM |
F08.00006: High temperature RIXS study of charge transfer excitations in cuprates Biqiong Yu, Kenji Ishii, Shun Asano, Masaki Fujita, Diego M Casa, Guichuan Yu, Martin Greven Resonant inelastic X-ray scattering (RIXS) is a promising technique to study momentum-resolved electronic excitations in strongly correlated materials. Here we present results of a recent Cu K-edge RIXS study on the archetypal hole-doped cuprate La2-xSrxCuO4 and electron-doped cuprate Nd2-xCexCuO4. Our measurements, which range from low temperature (15 K) to very high temperature (1200 K), indicate distinct spectral weight changes of charge-transfer excitations below ~ 2 eV. We will make a detailed comparison of the temperature dependent charge-transfer excitations in electron- and hole- doped cuprates. |
Tuesday, March 5, 2019 12:27PM - 12:39PM |
F08.00007: Doping Dependence of Charge Density Wave in Bi-2212 Cuprate Superconductors Haiyu Lu, Matthias Hepting, Makoto Hashimoto, Yu He, Sudi Chen, Kejun Xu, Shigeyuki Ishida, Yoshiyuki Yoshida, Hiroshi Eisaki, Riccardo Arpaia, Giacomo Ghiringhelli, Lucio Braicovich, Brian Moritz, Edwin Huang, Kurt Kummer, Nicholas B Brookes, Zhi-Xun Shen, Thomas Devereaux, Wei-Sheng Lee The origin of the charge density wave (CDW) in high-temperature superconductor, its interplay with superconductivity, and more importantly, to which extent it influences lattice and charge degrees of freedom remain an active area of research. To gain further insights into these questions, it is necessary to characterize its doping and temperature dependence. We performed high energy resolution momentum-resolved resonant inelastic soft x-ray scattering (RIXS) experiments at the Cu L3-edge on the high-temperature superconductor Bi2Sr2CaCu2O8+x with the doping level across the entire phase diagram (Antiferromagnetic, underdoped, optimally doped, and overdoped). Doping dependence of the CDW, the associated phonon softening, and excitations will be discussed. |
Tuesday, March 5, 2019 12:39PM - 12:51PM |
F08.00008: Anisotropically damped magnetic excitations in La2-xSrxCuO4 Hannah Robarts, Stephen Hayden, Kejin Zhou
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Tuesday, March 5, 2019 12:51PM - 1:03PM |
F08.00009: Photo-enhanced metastable c-axis transport in stripe ordered cuprate La1.885Ba0.115CuO4 Kevin Cremin, Jingdi Zhang, Christopher Homes, Genda Gu, Zhiyuan Sun, Michael Fogler, Andrew Millis, Dimitri N Basov, Richard Douglas Averitt Numerous cuprate-based superconductors exhibit a complex interplay between spin order, charge order and superconductivity. Light-matter interaction can provide alternate pathways to initiate phase transitions via non-linear drive or by readjusting the energy landscape between competing order parameters. THz time domain spectroscopy is performed on stripe ordered La2-xBaxCuO4 (x = 0.115) to monitor the c-axis Josephson Plasma Resonance (JPR), which acts a direct probe of the superconducting dynamics following near-infrared excitation. After photo-excitation of the superconducting state with 1.55 eV pulses, we observe the emergence of a new long lived metastable state which displays a blue shifted plasma edge. This new phase is suggestive of enhanced c-axis transport not observed in equilibrium and has implications for superconducting fluctuations appearing above Tc in the charge ordered state. We also investigate the mechanism for how the electronic transition at 1.55 eV couples to c-axis vibrational modes which may aid in the superconducting fluctuations above Tc. |
Tuesday, March 5, 2019 1:03PM - 1:15PM |
F08.00010: Abstract Withdrawn
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Tuesday, March 5, 2019 1:15PM - 1:27PM |
F08.00011: Self-heating, phase coherence, and sidewall angle in stacked intrinsic Josephson junction Bi2Sr2CaCu2O8 terahertz sources Karen Kihlstrom, Timothy Benseman, Alexei E Koshelev, Ulrich Welp, Wai-Kwong Kwok, Kazuo Kadowaki The extremely anisotropic high-temperature superconductor Bi2Sr2CaCu2O8 contains stacked 'intrinsic' Josephson junctions with a large superconducting gap energy. Mesa-shaped devices constructed from this material are therefore a promising source of coherent, continuous-wave radiation in the 'terahertz gap' range. |
Tuesday, March 5, 2019 1:27PM - 1:39PM |
F08.00012: Evolution of charge order topology across a magnetic quantum phase transition in electron-doped cuprates Min Gu Kang, Jonathan Pelliciari, Alex Frano, Nicholas Breznay, Enrico Schierle, Eugen Weschke, Ronny Sutarto, Feizhou He, Padraic Shafer, Elke Arenholz, Mo Chen, Keto Zhang, Alejandro Ruiz, Zeyu Hao, Sylvia Lewin, James G. Analytis, Yoshiharu Krockenberger, Hideki Yamamoto, Tanmoy Das, Riccardo Comin Charge order is now accepted as an integral constituent of the phase diagram of cuprate high-temperature superconductors. Unlike nesting-induced Peierls density waves, the charge correlations in the CuO2 planes have been predicted to display a rich momentum space topology depending on the detailed fermiology of the system. However, to date charge order has only been observed along the high-symmetry Cu-O bond directions. Here, using resonant soft X-ray scattering, we investigate the evolution of the full momentum space topology of charge correlations in T’-Ln2CuO4 (Ln=Nd, Pr) as a function of intrinsic electron doping. We report that, upon electron doping the parent Mott insulator, charge correlations first emerge in a hitherto-unobserved form, with full (Cinf) rotational symmetry in momentum-space. At higher doping levels, the orientation of charge correlations is sharply locked to the Cu-O bond high-symmetry directions, restoring a more conventional bidirectional charge order with enhanced correlation lengths. Our charge susceptibility calculations closely reproduce the drastic evolution in the topology of charge correlations across an antiferromagnetic quantum phase transition, highlighting the interplay between spin and charge degrees of freedom in electron-doped cuprates. |
Tuesday, March 5, 2019 1:39PM - 1:51PM |
F08.00013: Study of radiation spectrum of Bi2Sr2CaCu2O8+d high-Tc superconducting terahertz emitters. Takanari Kashiwagi, Genki Kuwano, Takayuki Imai, Shungo Nakagawa, Yuuki Tanabe, Ryusei Ota, Kento Nakamura, Yukino Ono, Youta Kaneko, Shinji Kusunose, Manabu Tsujimoto, Takashi Yamamoto, Hidetoshi Minami, Richard Klemm, Kazuo Kadowaki In order to understand the emission characteristics of Bi2Sr2CaCu2O8+ d (Bi2212) high-Tc superconducting THz emitters, it is very important to clarify the Joule heating characteristics of the devices. Recently, in order to reduce the self-heating from the Bi2212-THz emitters, we have proposed a stand-alone mesa structure of Bi2212 single crystals and its sandwich structures. The radiation characteristics obtained from these devices indicate clearly that the thermal management of the THz emitters is most important issue in order to obtain good radiation performance and reproducibility. |
Tuesday, March 5, 2019 1:51PM - 2:03PM |
F08.00014: Optical perturbation of the "hole-pockets" in the underdoped high Tc superconducting cuprates Simon Freutel, Jonathon Rameau, Laurenz Rettig, Isabella Avigo, Manuel Ligges, Yoshiyuki Yoshida, Hiroshi Eisaki, John A. Schneeloch, Ruidan Zhong, Zhijun Xu, Genda Gu, Uwe Bovensiepen, Peter Johnson The high Tc superconducting cuprates are considered doped Mott insulators. As a function of doping and temperature there is a crossover from this regime into a phase characterized a Marginal Fermi Liquid. Several calculations of the doped Mott insulating phase indicate that the Fermi surface defines small pockets which at higher doping levels switch to a full closed Fermi surface, characteristic of a more metallic system. Here we use femtosecond laser based pump-probe techniques to investigate the structure of the Fermi surface in underdoped Bi2Sr2CaCu2O8+δ and compare it with that associated with the optimally doped material. We confirm the concept of a small pocket in the underdoped system consistent with theoretical predictions in this strongly correlated state. |
Tuesday, March 5, 2019 2:03PM - 2:15PM |
F08.00015: Pressure tuning of competing orders and superconductivity in Bi2Sr1.6La0.4CuO6 Jiawei Hu, Jie Xin, Xiao-Jia Chen, Viktor V. Struzhkin, Alexander Goncharov, Hai-Qing Lin, Cheng-tian Lin Systematic measurements of Raman scattering and magnetic susceptibility are performed on an optimally doped Bi2Sr1.6La0.4CuO6 with well characterized change density wave and pesudogap. A pressure-temperature phase diagram is obtained for this superconductor. The superconducting transition temperature Tc is found to initially increase with increasing pressure and then decreases upon heavy compression after passing a maximum at a critical pressure of 15 GPa. Meanwhile, either the charge-density-wave or the pesudogap is suppressed by the applied pressure with the disappearance of their lock-in or opening temperature at the critical pressure. The significant Tc enhancement in the low-pressure region benefits from the suppression of the competing orders. The phonon frequency of the oxygen atoms in the charge reservoir is observed to be closely correlated to the evolution of Tc with pressure. Meanwhile, the emergence of the charge disorder and its growth with pressure are detected after the critical pressure, indicating its unfavorable role to superconductivity. A complete picture for superconductivity with the competing orders, reservoir layer, and charge disorder for a cuprate superconductor is thus established. |
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