Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session B06: Cuprates and RelatedFocus
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Sponsoring Units: DCMP Chair: Jasminka Terzic, National High Magnetic Field Laboratory Room: BCEC 109A |
Monday, March 4, 2019 11:15AM - 11:27AM |
B06.00001: Magnetic-field-tuned superconducting quantum phase transition in highly overdoped Bi2+xSr2-xCuO6+δ Jasminka Terzic, Paul G. Baity, Bal K Pokharel, Lily Stanley, Dragana Popovic, Shimpei Ono The conventional picture of overdoped cuprates as BCS d-wave superconductors has been recently challenged, with the roles of disorder and quantum fluctuations under debate. To address these questions, we focus on the highly overdoped regime, which we have explored via measurements of linear transport and voltage-current characteristics on the hole-doped, La free, Bi2+xSr2-xCuO6+δ (Bi2201) single crystals with zero-resistance transition temperatures Tc ~ 5 K. Measurements were performed in magnetic fields (H) up to 45 T and temperatures (T) down to 17 mK. We discuss the nature of the H-field-tuned superconducting quantum phase transition and the high-field ground state, and present the T-H phase diagram for the highly overdoped Bi2201. |
Monday, March 4, 2019 11:27AM - 11:39AM |
B06.00002: Scale-Invariant transport in high-temperature superconductors Arkady Shekhter, Brad Ramshaw, Kimberly Modic, Laurel Winter, Seiki Komiya, Shimpei Ono, Fedor Balakirev, Jonathan B Betts, Gregory Scott Boebinger, Ross McDonald We report high-magnetic-field (up to 93T) Hall measurements in LSCO cuprates superconductor near critical doping (x=0.20). The observed Hall behavior exhibits a crossover from a low-field to high-field behavior in a broad range of temperatures. Such Hall behavior is incompatible with Fermi surface quasiparticle transport in the strange metal state. |
Monday, March 4, 2019 11:39AM - 11:51AM |
B06.00003: Optical Thermal Diffusivity Measurement in Bad Metals Jiecheng Zhang, Erik Kountz, Aharon Kapitulnik, Richard L. Greene Local measurements of thermal diffusivity are used to analyze the transport of heat in the bad metallic regime of several strongly correlated materials. Thermal diffusivity DQ was measured for several cuprate systems in their so-called bad metal regime, including both electron and hole doped cuprates. The temperature dependence of normal state resistivity of these systems are either linear or close-to-quadratic, while the overall magnitudes exceed the Mott-Ioffe-Regel limit at approximately 250K, indicating failure of the conventional quasiparticle transport picture. We found that the various doping of (Nd/Pr/Sm)1-xCexCuO4 all have T-linear DQ-1. We interpret our results through a strong electron-phonon scattering picture where both electron and lattice system saturates a quantum scattering time bound of ~h/kBT, and the slope of the T-linear DQ-1 is associated with a characteristic intermediate speed between the speed of sound and the Fermi velocity. Our results suggest that neither well-defined electron nor phonon quasiparticles might be present in these systems, and that thermal transport is carried out by a collective ”soup” of strongly coupled electrons and phonons. |
Monday, March 4, 2019 11:51AM - 12:03PM |
B06.00004: High Temperature Electrical Transport in Electron-Doped Cuprates Nicholas Poniatowski, Tarapada Sarkar, Pampa Mandal Sarkar, Richard L. Greene Although the origin of high-temperature superconductivity in the cuprates has eluded the community for decades, the normal state of these materials is similarly enigmatic. The universal T-linear electrical resistivity observed in hole-doped compounds such as YBCO and LSCO, persistent to high temperatures, is thought to violate the Mott-Ioffe-Regel (MIR) limit on the scattering rate, where traditional Boltzmann theories of transport break down. Consequently, the normal state of these and other strongly correlated materials are now considered a new phase of matter, the "strange metal." We report resistivity and magnetoresistivity (MR) measurements of the electron doped cuprate La2-xCe2CuO4 (LCCO) from 100K to above room temperature and relate our findings to the hole-doped side of the phase diagram. By studying slightly underdoped samples (x=.08, .10) in proximity to the antiferromagnetic phase (without a field), we are able probe the strange metallic regime in the vicinity of the MIR bound without having to resort to excessively high temperatures. For other dopings, we report new MR data. |
Monday, March 4, 2019 12:03PM - 12:15PM |
B06.00005: Hall coefficient in two-dimensional metals with spiral magnetic order and application to cuprate high-Tc superconductors Johannes Mitscherling, Walter Metzner Charge transport measurements in high magnetic fields recently shed new light on the non-superconducting ground state in cuprate high-Tc superconductors [1]. In particular, Hall measurements yield a drop of the Hall number indicating a phase transition associated with a Fermi surface reconstruction. On the theoretical side, spiral magnetic order (or quasi-order) remains a hot candidate for the Fermi surface reconstruction mechanism. |
Monday, March 4, 2019 12:15PM - 12:27PM |
B06.00006: Correlation between scale-invariant normal state resistivity and superconductivity in an electron-doped cuprate Tarapada Sarkar, Pampa Mandal Sarkar, Nicholas R. Poniatowski, Mun Keat Chan, Richard L. Greene An understanding of the normal state in the high-Tc superconducting cuprates is crucial to the understanding of the long-standing problem of the origin of the superconductivity itself. This so-called “strange metal” state is thought to be associated with a quantum critical point (QCP) hidden beneath the superconductivity. In electron-doped cuprates, it is possible to access the normal state at very low temperatures and low magnetic fields to study this putative QCP and to probe the T→ 0 K state of these materials. We report measurements of the low temperature normal state magnetoresistance (MR) of the n-type cuprate system (LCCO) and find that it is characterized by a linear-in-field behavior, which follows a scaling relation with applied field and temperature, for doping (x) above the putative QCP (x= 0.14). This unconventional behavior suggests that magnetic fields probe the same physics that gives rise to the anomalous low-temperature linear-in-T resistivity. The magnitude of the linear MR decreases as Tc decreases and goes to zero at the end of the superconducting dome (x ~0.175) above which a conventional quadratic MR is found. we discuss the correlation between Linear-in-T and Linear-in-H resistivity with the superconductivity. |
Monday, March 4, 2019 12:27PM - 12:39PM |
B06.00007: short-range pair density wave in cuprates Zhehao Dai, Yahui Zhang, Senthil Todadri, Patrick Lee We analyze recent STM results on period-8 density wave in the cuprate vortex halo and provide a theory of short-range pair density wave to explain quantum oscillation above Hc2 and the electron gap in the anti-nodal region in underdoped cuprates. |
Monday, March 4, 2019 12:39PM - 12:51PM |
B06.00008: Gauge theory for the cuprates near optimal doping Subir Sachdev, Harley Scammell, Mathias Scheurer, Grigory Tarnopolsky We propose a SU(2) gauge theory with fermionic low-energy excitations as an effective field theory for the cuprate high-temperature superconductors. For the hole-doped compounds, the theory describes fluctuating incommensurate spin-density waves. While we recover the conventional Fermi-liquid state as the confining phase of the theory at large doping, there is a quantum phase transition to a Higgs phase corresponding to the pseudogap at low doping. Depending on details of the theory, the Higgs phase shows one or more of charge-density wave, Ising-nematic, scalar spin chirality, and Z2 topological order. For the electron-doped systems, we assume commensurate spin-density wave fluctuations and there is only a crossover between the confining and the Higgs regime, with an exponentially large confinement length deep in the Higgs regime. For both the electron- and hole-doped systems, the electronic spectral function shows small Fermi surfaces at scales shorter than the confinement length. Finally, we present a large-N analysis of the deconfined quantum criticality of the Higgs transition. |
Monday, March 4, 2019 12:51PM - 1:03PM |
B06.00009: Normal-state optical conductivity and linear resistivity of the cuprates from tightly bound pre-formed pairs Long Zou, Shengtao Jiang, Wei Ku We investigate anomalous normal-state in-plane resistivity and optical conductivity of cuprates by using multi-orbital bose-liquid model. Specifically, we assume that the charge carriers in cuprate are tightly bound pre-formed pairs. We show the low-energy optical spectrum involving both intra- and inter-band excitation. While inter-band excitation explain the continuous spectrum and its contribution around the van-Hove singularities of the pre-formed pairs can reproduce the experimental observed onset near 1000cm-1, the intra-band excitation will mainly contributes to low frequency conductivity and gives rise to linear resistivity without saturation. Instead of considering about the mean free path, we demonstrate this universal bad metal behavior originate from the continuously decreasing height of low-frequency peak since its weight transfers to high energy region with temperature.Our study reveals the bosonic nature of the low-energy carriers and provides a strong support for the picture of tightly bound preformed pairs in describing the high-temperature superconductivity and other low-energy physics of the cuprates. |
Monday, March 4, 2019 1:03PM - 1:15PM |
B06.00010: Slow magnetic fluctuations in the pseudogap phase of YBa2Cu3Oy Jian Zhang, Douglas E. MacLaughlin, Zhaofeng Ding, Cheng Tan, Oscar Bernal, Pei-Chun Ho, Gerald D Morris, Akihiro Koda, Adrian Hillier, Stephen P. Cottrell, Peter J. Baker, P. K. Biswas, Yanxing Yang, Zihao Zhu, Jun Qian, Yan Wan, Xin Yao, Lei Shu We report broken time-reversal symmetry in the pseudogap state of underdoped single crystalline YBa2Cu3Oy using muon spin relaxation technique. Slow magnetic fluctuations are observed below the characteristic pseudogap onset temperature T*, signaled by the Redfield relation between the Lorentzian relaxation rate of the positive muons and the applied field along the muon initial spin polarization. We measured the temperature dependence of the local field and compared it with the order parameter measured by neutron scattering. The slow frequency scale of the fluctuations, 5 orders of magnitude below the energy scale of the pseduogap energy, implies that time-reversal symmetry is broken for properties intermediate between the two scales, but raises the question of the nature of the quantum fluctuations responsible for time-reversal not being absolutely broken. |
Monday, March 4, 2019 1:15PM - 1:27PM |
B06.00011: Imaging Domains and Domain Walls in High-Temperature Superconductor Tadesse Assefa, Yue Cao, Ross Harder, Ian Keith Robinson, John Tranquada, Genda Gu Phase transition, Symmetry breaking and recovery in condensed matter systems are closely related to the exotic physical properties of strongly correlated materials such as superconductivity, magnetism, ferroelectricity, etc. A key signature of broken symmetry is the formation of structural domains of few nanometer size. Bragg coherent X-ray diffraction techniques can enable novel experimental opportunities to directly visualize symmetry changes in these materials through domain structure. We have pushed Bragg Coherent Diffractive Imaging (BCDI) into the cryogenic regime where most phase transitions in quantum materials reside. Utilizing coherent photons at 34-ID-C beamline of the Advanced Photon Source, we image the structural domain evolution of La2-xBaxCuO4,x=1/8 sample during the low-temperature-orthorhombic (LTO) to high temperature tetragonal (HTT) phase transition. These phases break the local four-fold rotational symmetry of its high temperature tetragonal (HTT) structure and our preliminary data suggests the low-temperature-orthorhombic (LTO) phase is not pinned to local crystal disorder or defects. |
Monday, March 4, 2019 1:27PM - 1:39PM |
B06.00012: What happened at 19% doping in Bi2212: an ARPES perspective Sudi Chen, Makoto Hashimoto, Yu He, Dongjoon Song, Kejun Xu, Junfeng He, Donghui Lu, Hiroshi Eisaki, Zhixun Shen In the hole-doped cuprate superconductors, the special doping p = 0.19 has attracted considerable research interest. Various anomalies have been observed at this doping and associated with fascinating physics, for example the change from small to large Fermi surface, the termination of the pseudogap, the recovery of coherence, and the possibility of a quantum critical point. In this talk we present a systematic ARPES study across 84 temperature-doping points in Bi2212 near p = 0.19. The results provide important insights about the nature of this special doping and the phenomenology of the cuprates. |
Monday, March 4, 2019 1:39PM - 1:51PM |
B06.00013: Anomalous Dimensions for Conserved Currents from Holographic Dilatonic Models to Superconductiv Philip Phillips, Kridsanaphong Limtragool, Gabriele La Nave Anomalous Dimensions for Conserved Currents from Holographic Dilatonic Models to Superconductivity |
Monday, March 4, 2019 1:51PM - 2:03PM |
B06.00014: A novel solution of the 2D Hubbard model within a 4-pole approximation: electronic dispersion and Fermi surface evolution Andrea Di Ciolo, Adolfo Avella We present and characterize a novel solution of the 2D Hubbard model within the Composite Operator Method [1,2] in a 4-pole approximation [3]. We have chosen a basis of four fields: the two Hubbard operators plus two fields describing the Hubbard transitions dressed by nearest-neighbor spin fluctuations, which play a crucial role for strong correlations. This 4-pole solution performs very well once compared with advanced (semi-)numerical methods for all relevant values of interaction, doping and temperature, being considerably less computational-resource demanding. By carefully treating spin fluctuations and featuring momentum selectivity, this solution can address the underdoped-cuprate puzzle (Fermi arcs, pseudogap, non-Fermi liquid behavior, …). We adopt this approximation to study the single-particle properties of the model in the strong coupling regime, where spin fluctuations are responsible for anomalous features in the analyzed properties. We focus on the investigation of the electronic dispersion and of the Fermi surface, studying their evolution with doping and temperature. |
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