Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session W49: Superconductivity and Competing phases |
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Sponsoring Units: DCMP Chair: David Tanner, University of Florida Room: Mile High Ballroom 1B |
Friday, March 6, 2020 8:00AM - 8:12AM |
W49.00001: Signatures of a pair density wave in striped cuprates at high magnetic fields (H) Paul Baity, Zhenzhong Shi, Jasminka Terzic, Dragana Popovic, Takao Sasagawa In underdoped cuprates, a putative pair density wave (PDW) state has been suggested to be responsible for the pseudogap regime, but the evidence for a PDW remains inconclusive. To test the interlayer frustration, the crucial component of the PDW picture, we performed transport measurements on La1.7Eu0.2Sr0.1CuO4 and La1.48Nd0.4Sr0.12CuO4 with “striped” spin and charge orders in perpendicular magnetic fields Hperp, and we also applied an additional field parallel to CuO2 layers (Hpara). We detected several phenomena predicted to arise from the existence of a PDW, including an enhancement of interlayer superconducting (SC) phase coherence with increasing Hpara. Our results are consistent with the presence of local, PDW pairing correlations that compete with the uniform SC order at temperatures Tc0 < T < (2-6)Tc0, where Tc0 is the zero-field SC transition temperature, and become dominant at high enough Hperp as T→0. |
Friday, March 6, 2020 8:12AM - 8:24AM |
W49.00002: Re-investigating the pseudogap phase of cuprates. Paolo Abrami, Sven Badoux, Antony Carrington The nature of the pseudogap state and the role it plays in the rich phase diagram of cuprate superconductors is yet to be fully understood. It is still an open question whether the transition to this state is a true phase transition or a slow crossover. A further question is whether the phase transition terminates at a zero temperature quantum critical point and what influence this has on the superconductivity. Recently, measurements of in-plane magnetic torque have suggested an abrupt transition close to the estimated edge of the pseudogap phase; suggesting a thermodynamic transition to an electronically nematic state. Here were further investigate these effects in different high Tc cuprates and how extrinsic effects can influence the signals seen. |
Friday, March 6, 2020 8:24AM - 8:36AM |
W49.00003: Diffuse Scattering Studies of Local Correlations in ErBa2Cu3O6+x Bisham Poudel, Bogdan M Dabrowski, Daniel Phelan, Matthew Krogstad, Raymond Osborn, Stephan Rosenkranz, Omar Chmaissem The origin of unconventional superconductivity in cuprate superconductors remains a great challenge. Early observations of stripe correlations in La2-x-yNdxSryCuO4 confirmed the existence of spin and charge density wave orders near a “magical” p = 1/8 hole-doping where superconductivity disappears. At about the same time, ARPES measurements observed a pseudogap at temperatures much higher than TC. The observation of CDW and pseudogap states appearing together and vanishing near optimal doping led to the speculation that these parameters are correlated and have a common origin. However, with the detection of weak charge density waves in YBCO near optimal doping (away from p = 1/8), these claims need to be re-evaluated. In that regard, rare-earth crystal field spectroscopy, used as a probe of the local structural and electronic environment in ErBa2Cu3O6+x, provided evidence for charge-transfer between the copper chains and planes and the formation of clusters with three distinct states. In this talk, I will discuss recent single crystal diffuse scattering work to elucidate the nature of local short-range order and its correlation with CDW and the pseudogap states. |
Friday, March 6, 2020 8:36AM - 8:48AM |
W49.00004: Spatially Inhomogeneous Competition between Superconductivity and the Charge Density Wave in YBa2Cu3O6.67 Jaewon Choi, Oleh Ivashko, Elizabeth Blackburn, Ruixing Liang, Douglas Andrew Bonn, Walter N Hardy, Alexander Holmes, Niels Bech Christensen, Markus Huecker, Simon Gerber, Olof Gutowski, Uta Ruett, Martin von Zimmermann, Edward M. Forgan, Stephen Hayden, Johan Chang Application of magnetic field induces new charge density wave (CDW) order in the high-temperature superconductor YBa2Cu3O7−x (YBCO), which is defined here as ferro-coupled CDW (F-CDW). It can be differentiated from the conventional antiferro-coupled CDW (or AF-CDW) by their c-axis correlations. This discovery has provoked a number of questions such as how does superconductivity compete with two CDW orders? and are either of these orders responsible for the electronic reconstruction? High-energy x-ray diffraction experiements were carried out to find a clue to those questions. The intensity of F-CDW order in YBa2Cu3O6.67 was investigated as a function of magnetic field and temperature. We found that F-CDW order exists from low-field range B ~ 5 T, and regions of the sample with F-CDW order suppress superconductivity stronger than those with AF-CDW order. It implies that the superconducting state in some regions is more fragile than that in the other regions. In addition, F-CDW order has sufficiently long correlation length to explain the reconstruction of the electronic state. Our study sheds a light on the role of F-CDW order in superconducting and normal state properties of underdoped YBCO. |
Friday, March 6, 2020 8:48AM - 9:00AM |
W49.00005: No pseudogap magnetism detected in optimally to heavily overdoped Bi2+xSr2-xCaCu2O8+d single crystals by μSR Shayan Gheidi, Andre M Côté, Sarah Dunsiger, Kolawole Abayomi Akintola, Alex Fang, Shyam Sundar, Genda Gu, Jeff Sonier Weak, temperature-dependent, quasi-static magnetism has been detected within the pseudogap (PG) phase of optimally-doped (Tc = 91 K) and overdoped (Tc = 80 K) Bi2+xSr2-xCaCu2O8+d (Bi2212) single crystals by zero-field (ZF) muon spin relaxation (mSR) [A. Pal et al., Phys. Rev. B 97, 060502(R) (2018)]. However, in this study it was not possible to determine whether the magnetism onsets at the PG temperature (T*) due to the occurrence of muon diffusion above T ~ 150 K. To address this issue, we performed a similar ZF-mSR investigation of overdoped single crystals (Tc = 70 K and 55 K) in which T* lies below the muon diffusion temperature. The results are similar to that obtained for the lower doped samples, indicating that the anomalous magnetism is independent of hole-doping concentration and thus apparently not associated with the PG. We have carried out additional ZF-mSR measurements on these samples using an ultra-low background spectrometer. The new measurements verify the source of the magnetism comes from the Bi2212 samples. Potential origins of the anomalous magnetism will be discussed. |
Friday, March 6, 2020 9:00AM - 9:12AM |
W49.00006: Nematic Cooper-pair mass renormalization in copper oxide superconductors Jonatan Wardh, Mats Granath, Jie Wu, Ivan Bozovic We show that the observation of rotational symmetry breaking from transverse resistivity measurements in the normal state of LaSrCuO by Wu et al1. can be accounted for by the thermal fluctuations of a 2D superconductor with significant in-plane phase stiffness anisotropy. The conductivity tensor is modeled by distinct normal state and paraconducting components, with different effective mass tensors corresponding in general to non-aligned nematic directors and different mass anisotropies. The model is supported by new experimental data showing the rotation of the measured nematic director in the presence of a magnetic field that suppresses superconductivity. The pair mass/phase stiffness anisotropy grows dramatically with underdoping, pointing to an exotic pseudogap state with quasi-one-dimensional pair fluctuations, despite a relatively weak single-particle anisotropy. |
Friday, March 6, 2020 9:12AM - 9:24AM |
W49.00007: Magnetic-field-tuned superconducting quantum phase transition in underdoped Bi2Sr2-xLaxCuO6+δ Jasminka Terzic, Bal Pokharel, Paul Baity, Lily Stanley, Dragana Popovic, shimpei ono In underdoped cuprates, the value of the upper critical magnetic field (Hc2) has been under debate. However, recent studies on the La-214 family have firmly established vortex phase diagrams that include an intermediate, viscous vortex liquid regime, regardless of the presence of charge order. We perform similar studies in underdoped Bi2Sr2-xLaxCuO6+δ (La-Bi2201), which exhibits short-range charge order, by measuring linear transport, voltage-current characteristics and Hall effect in H up to 45 T and temperatures (T) down to 0.017 K. Our data reveal an insulatinglike high-field normal state and a qualitatively the same vortex phase diagram as in underdoped La-214 cuprates, thus supporting the universality of the vortex phase diagram with an intermediate phase, i.e. the importance of quantum phase fluctuations as T→0, in underdoped cuprates. The properties of the apparent two-stage superconductor-insulator transition are discussed and compared to that in highly underdoped La2-xSrxCuO4. |
Friday, March 6, 2020 9:24AM - 9:36AM |
W49.00008: Incommensurability of the dynamic spin modulations in La2-xSrxCuO4 (x=0.12) Wei He, Jiajia Wen, K. M. Suzuki, Shun Asano, Wei Tian, Masaki Fujita, Young Sang Lee The high-temperature superconducting cuprates display intriguing physical phenomena due to the presence of competing or intertwined phases. One of the remarkable observations in both Sr-doped La2-xSrxCuO4 (LSCO) system and O-doped La2CuO4+y is the so-called Y-shift, which refers to a small shift of both spin density wave (SDW) and charge density wave (CDW) peak positions from the high-symmetry Cu-Cu bond direction. However, the ordering temperatures for the SDW and CDW are different. Above the superconducting transition temperature (Tc), there is only incipient spin fluctuation coexisting with the CDW order. In this talk, I will present our recent high-resolution inelastic neutron scattering experiment which characterized the Y-shift in the spin fluctuation regime in LSCO (x=0.12). The implication of the result will be discussed. Our study provides important information on the nature of the spin fluctuation in this system. |
Friday, March 6, 2020 9:36AM - 9:48AM |
W49.00009: Emergence of superconductivity in two transition metal chalcogenides Nikolaos Biniskos, Sajna Hameed, Damjan Pelc, Yuan Li, Xiangde Zhu, Cedomir Petrovic, Martin Greven Superconducting (SC) and charge-density-wave (CDW) states are pair condensates of electrons and of electrons and holes, respectively. In many quantum materials, these two states are found to coexist or compete. Transition-metal chalcogenides such as TaSe2−xSx [1] and ZrTe3−xSex [2] exhibit both SC and CDW phases and may be viewed as model systems to study the interplay between these two types of order. In both systems, substitutional disorder enhances SC order and suppresses CDW order [1,2]. We use AC nonlinear magnetic response, a probe that was recently shown to be highly sensitive to SC fluctuations [3], to correlate the diamagnetic response above the superconducting transition temperature with the substitutional disorder. Our results indicate rather narrow SC fluctuation regimes, yet with unconventional temperature dependences of the diamagnetic signal. We discuss these findings in the context of recent work on oxide superconductors [3]. |
Friday, March 6, 2020 9:48AM - 10:00AM |
W49.00010: Direct observation of an incommensurate charge density wave in the superconductor Ta4Pd3Te16 Zhenzhong Shi, Stephen J Kuhn, Felix Flicker, William Steinhardt, Sachith Dissanayake, Toni Helm, Jooseop Lee, Jacob Ruff, Gilberto F L Fabbris, David E Graf, Joerg Strempfer, Daniel Haskel, Sara Haravifard The various electronic instabilities such as superconductivity (SC) and charge density wave (CDW) in low dimensions often conspire to determine some novel ground states in strongly correlated systems. In this talk we present our experimental and theoretical results. We report the observation of a highly unusual incommensurate charge density wave (CDW) in the superconductor Ta4Pd3Te16, using synchrotron X-ray diffraction. Additionally, our de Haas-van Alphen (dHvA) quantum oscillation measurements detect no evidence of Fermi surface reconstruction across the CDW transition. The temperature-pressure phase diagram was also determined, and the SC dome is found to be centered at the pressure where the CDW vanishes. |
Friday, March 6, 2020 10:00AM - 10:12AM |
W49.00011: Nematic order and Charge order in Ba0.6Sr0.4Ni2As2 Prathum Saraf, Chris Eckberg, Sangjun Lee, John Collini, Stella Sun, Daniel J Campbell, Jeffrey Lynn, Peter Abbamonte, Johnpierre Paglione Studies in the Cuprates and the Fe-based superconductors have hinted at a relationship between charge order order and superconductivity. The recent study on Ba1-xSrxNi2As2 shows strong nematic susceptibility for the B1G symmetry with increasing Sr doping corresponding to an enhancement in Tc. Ba0.6Sr0.4Ni2As2 is at the border of lattice driven nematic order and electronically driven nematic order. We report on X-ray and Neutron measurements on Ba0.6Sr0.40Ni2As2 that show the existence of three charge density waves. An incommensurate CDW in the tetragonal phase with q=(0.27,0,0) and two commensurate CDWs in the triclinic phase with q=(0.33,0,0) and (0.5,0,0) are observed. The commensurate CDWs in the triclinic phase exist down to base temperature. We will discuss these results as well as elastoresistance measurements in Ba0.6Sr0.4Ni2As2. |
Friday, March 6, 2020 10:12AM - 10:24AM |
W49.00012: Charge Order in Tunable Electronic Nematic Superconductor Ba1-xSrxNi2As2 John Collini, Sangjun Lee, Stella Sun, Chris Eckberg, Jeffrey Lynn, Peter Abbamonte, Johnpierre Paglione Recent discoveries of charge order in the cuprates and electron nematic order in the iron-based superconductors has pointed towards the possibilities of both orderings being tied to mechanisms of high Tc superconductivity.The Ba(1-x)Sr(x)Ni2As2 system, closely related to the BaFe2As2 system, has recently been shown to exhibit both types of ordering without the presence of any magnetic order. We report single crystal X-ray diffraction observations that show a unidirectional charge order with wavevector (0.27,0,0) in BaNi2As2 decays and vanishes by x=0.65. We also show that the (0.33,0,0) CDW in the triclinic phase evolves into a (0.5,0,0) CDW by x=0.65. The evolution of the charge order in this system correlates well with the reported evolution of nematicity and superconducivity, suggesting a strong link between the three phases. |
Friday, March 6, 2020 10:24AM - 10:36AM |
W49.00013: Interstitial Oxygen Dopant Dynamics in La2CuO4+y Probed by Coherent X-rays Mingde Jiang, Wei He, Jiajia Wen, Andrei Fluerasu, Yugang Zhang, Lutz Wiegart, Young Sang Lee Oxygen doping La2CuO4 (LCO) yields the superconductor La2CuO4+y with the highest Tc in the LCO family. The interstitial oxygen dopants are mobile and can be annealed to form an ordered lattice, manifested as a satellite Bragg peak in x-ray diffraction. We present x-ray photon correlation spectroscopy (XPCS) data, measuring the dynamic timescale of the corresponding oxygen ordering diffraction peaks in order to infer the interstitial oxygen dopant mobility and its temperature dependence. |
Friday, March 6, 2020 10:36AM - 10:48AM |
W49.00014: An evidence of the three-dimensional superconductivity evolution through apical oxygen in YBCO Hai Huang, Sang Jun Lee, Masaki Fujita, Terukazu Nishizaki, Chi-Chang Kao, Jun-Sik Lee Superconductivity in the high-Tc cuprates originates from transport phenomena in their universal structural CuO2 plane. Meanwhile, the role of the apical oxygen which locates between CuO2 planes has brought significant attention. This is because the superconducting temperature (Tc) varies based on cuprates, even though they have the same CuO2 structure and doping. Here, we investigated the oxygen order at the Cu-O chain layer in YBa2Cu3O6.73 (YBCO), which is connected with CuO2 plane through the apical oxygen. For this purpose, we performed resonant soft x-ray scattering measurement around the Cu L3-edge. We found that the evolution of the three-dimensional (3D) superconductivity in YBCO is strongly correlated with the oxygen order. More details will be introduced in the presentation. |
Friday, March 6, 2020 10:48AM - 11:00AM |
W49.00015: Fast moving superconducting vortices and determination of the critical current in high pulsed magnetic fields Boris Maiorov, Maxime Leroux, Ivan Nekrashevich, Masashi Miura, Fedor Balakirev, Leonardo Civale Expanding non-linear transport (I-V) studies to magnetic fields above those accessible by DC magnets can bring valuable information about systems such as superconductors, charge-density waves and topological semi-metals. All-superconducting very-high field magnets also make it technologically relevant to study vortex matter in this regime. However, pulsed magnetic fields reaching 100T in milliseconds impose technical and fundamental challenges that have prevented the realization of these studies. Here, we present a fast I-V DC technique that enables determination of the superconducting critical current in pulsed magnetic fields, beyond the reach of DC magnets. We demonstrate this technique on Cu- and Fe-based superconductors on single-crystalline and metallic substrates with excellent agreement with DC field measurements. The I-V characteristics change with the magnetic field rate (dH/dt). We capture this unexplored vortex physics through a model based on the broken symmetry of the vortex velocity profile produced by the applied current |
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