Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session K41: Mainly Spectroscopic Probes of CDW Phases in Cuprates |
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Sponsoring Units: DCMP Chair: Michael Sentef, Hamburg University Room: 388 |
Wednesday, March 15, 2017 8:00AM - 8:12AM |
K41.00001: Fluctuating Charge-Order in Optimally Doped Bi- 2212 Revealed by Momentum-resolved Electron Energy Loss Spectroscopy Ali Husain, Sean Vig, Anshul Kogar, Vivek Mishra, Melinda Rak, Matteo Mitrano, Peter Johnson, Genda Gu, Eduardo Fradkin, Michael Norman, Peter Abbamonte Static charge order is a ubiquitous feature of the underdoped cuprates. However, at optimal doping, charge-order has been thought to be completely suppressed, suggesting an interplay between the charge-ordering and superconducting order parameters. Using Momentum-resolved Electron Energy Loss Spectroscopy (M-EELS) we show the existence of diffuse fluctuating charge-order in the optimally doped cuprate Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (Bi-2212) at low-temperature. We present full momentum-space maps of both elastic and inelastic scattering at room temperature and below the superconducting transition with 4meV resolution. We show that the ``rods'' of diffuse scattering indicate nematic-like fluctuations, and the energy width defines a fluctuation timescale of $\sim$160 fs. We discuss the implications of fluctuating charge-order on the dynamics at optimal doping. [Preview Abstract] |
Wednesday, March 15, 2017 8:12AM - 8:24AM |
K41.00002: Doping-dependence of CDW Order in Bi2201, Measured by Phase-Sensitive STM Tatiana A. Webb, Yang He, Michael C. Boyer, Eric W. Hudson, Mohammad H. Hamidian, Jennifer E. Hoffman The cuprate phase diagram shows a charge density wave (CDW) dome within the pseudogap regime and intersecting the superconducting dome. However, there are important variations among members of the cuprate high-Tc family that can yield deep insight into how the phases interact. Here, we use scanning tunneling microscopy to investigate the doping dependence of the CDW order in (Bi,Pb)$_2$(Sr,La)$_2$CuO$_{6+\delta}$ (Bi2201). Sublattice-resolved phase sensitivity allows us to disentangle electronic components with different intra-unit cell symmetry. The energy and doping dependent evolutions show a connection with the superconducting and pseudogap phases. [Preview Abstract] |
Wednesday, March 15, 2017 8:24AM - 8:36AM |
K41.00003: Precursor Charge Density Waves in La1.875Ba0.125CuO4 Hu Miao, Y Peng, A Amorese, F Yakhou-Harris, K Kummer, N Brookes, J Lorenzana, G Seibold, G Gu, G Ghiringhelli, L Braicovich, M Dean The observation of charge density wave (CDW) correlations in numerous different samples has provided increasing support to the concept that these correlations are an intrinsic property of the high temperature superconducting cuprates. It has long been hypothesized that long-range CDW order arises from the pinning of precursor high-temperature CDW fluctuations, but while precursor spin density wave (SDW) correlations have been studied in detail, the corresponding transition between long-range ordered and precursor CDW correlations has never been observed. Here, using resonant inelastic x-ray scattering (RIXS), we report the discovery of precursor CDW correlations in La1.875Ba0.125CuO4. [Preview Abstract] |
Wednesday, March 15, 2017 8:36AM - 8:48AM |
K41.00004: Charge order correlations in Bi-based high-temperature cuprate superconductors measured by resonant x-ray scattering. Eduardo da Silva Neto, Matteo Minola, Fabio Boschini, Martin Bluschke, Alex Frano, Ronny Sutarto, Enrico Schierle, Feizhou He, Eugen Weschke, George Sawatzky, Bernhard Keimer, Andrea Damascelli We use resonant x-ray scattering to measure the doping dependence of the charge order (or charge density wave) in the BSCCO 2212 high-temperature superconductor. We detect the charge order in the underdoped regime (between 0.07 hole doping and optimal doping). We also find that the charge order wave vector is doping dependent spanning Q$=$0.25 to Q$=$0.29, following inter-pocket scattering. Furthermore, our bulk sensitive results show an equivalence to the charge order previously measured on the surface of BSCCO 2212 by scanning tunneling spectroscopy [E. H. da Silva Neto, et al. Science 343, 393 (2014)]. [Preview Abstract] |
Wednesday, March 15, 2017 8:48AM - 9:00AM |
K41.00005: Signature of charge density wave excitations in Bi2212 via ultrahigh resolution RIXS Wei-Sheng Lee, Laura Chaix, Giacomo Ghiringhelli, Yingying Peng, Makoto Hashimoto, Brian Moritz, Kurt Kummer, Nick Brookes, Yu He, Sudi Chen, S. Ishida, Hiroshi Eisaki, Lucio Braicovich, Zhi-Xun Shen, Thomas Devereaux, Wei-Sheng Lee Low energy excitations in heavily underdoped Bi$_2$Sr$_2$CaCu$_2$O$_8$ crystals were investigated using resonant inelastic soft x-ray scattering (RIXS) measurement at the Cu L3-edge with an ultrahigh energy resolution of 40 meV. In the quasi-elastic region, an incommensurate charge density wave (CDW) with a wavevector of 0.3 reciprocal lattice units are observed, confirming the existence of a CDW in this compound. Importantly, we observe signatures of dispersive CDW excitations that emanate from the CDW wavevector and intersect with bond-stretching phonons, causing an intensity anomaly at a wavevector away from the CDW wavevector. Temperature dependent measurement will also be discussed. [Preview Abstract] |
Wednesday, March 15, 2017 9:00AM - 9:12AM |
K41.00006: Charge Order and (001) Order in Superoxygenated Lanthanum Cuprates Zhiwei Zhang, Z.-H. Zhu, Ronny Sutarto, Feizhou He, William A. Hines, Joseph I. Budnick, F.-C. Chou, Barrett Wells Resonant elastic X-ray scattering has become a powerful technique in studying subtle charge, orbital, and nematic ordering in many correlated electron compounds, especially in cuprate superconductors. (La, Sr)CuO$_{4+\delta}$ is a less-studied but important hole doped superconductor where favored electronic phases spatially segregate in the phase diagram. In particular, one of the more prominent stable phases occurs at 1/8th doping with magnetic stripe scattering which is particularly sharp. Here we report a study in the charge order in this material with and without Sr substitutional doping. Charge ordering is exceedingly difficult to measure in these compounds for reasons that remain unsolved. In a particularly advantageous case we detected a resonant peak at $h=0.25$ at Cu $L_3$ edge whose temperature dependence reflects a transition temperature $\sim 50$K. Further, we observed the nominally disallowed (001) diffraction peak at a resonance energy between the O pre-edge and $K$ edge. This resonant (001) is reminiscent of a nematic order study in other cuprate superconductors, but the detailed energy dependence is quite different. We discuss the implications in light of electronic phase separation. 1. A.J. Achkar et al., Science 351, 6273 (2016) [Preview Abstract] |
Wednesday, March 15, 2017 9:12AM - 9:24AM |
K41.00007: Charge ordering in electron-doped infinite-layer cuprate Sr$_{1-x}$La$_x$CuO$_2$ Haofei Wei, Chiara Sacco, Alice Galdi, Christopher McMahon, Jacob Ruf, Cissy Suen, Ronny Sutaro, Feizhou He, Luigi Maritato, Darrell Schlom, David Hawthorn, Kyle Shen Charge ordering has emerged as a likely candidate for a universal ordering parameter in both hole- and electron-doped cuprates. In the electron-doped cuprates, however, charge order has only been detected in the R$_{2-x}$Ce$_x$CuO$_4$ (R=La,Nd) family. With its simple structure lacking both structural distortions and magnetic ions, the infinite-layer cuprate Sr$_{1-x}$La$_x$CuO$_2$ represents an important model system for studying charge ordering in electron-doped cuprates. Here, we use resonant elastic x-ray scattering to study charge ordering in Sr$_{1-x}$La$_x$CuO$_2$. Using a quantitative model to account for the fluorescent background, we detect signatures of charge order in several samples with doping near x=0.07. We find the ordering wavevector of the charge order to be Q=(0.13$\pm$0.02, 0, L), significantly smaller than has been observed in other cuprates. We discuss the relationship between the charge order and the Fermi surface in this material. [Preview Abstract] |
Wednesday, March 15, 2017 9:24AM - 9:36AM |
K41.00008: Local charge density and its variation in cuprate superconductors from NMR Michael Jurkutat, Steven Reichardt, Andreas Erb, Juergen Haase It was shown that NMR provides a quantitative measure of local charge at Cu and O in the CuO$_2$ plane of cuprate superconductors. A phase diagram in terms of these local charges, rather than total doping, reveals unsuspected insight into material-specific differences, while providing a unifying view of all cuprates. It is the sharing of the inherent Cu hole with O, which is intimately linked with the charge transfer gap and which determines the maximum Tc and superfluid density. Thus, one has a material chemistry parameter measurable even at room temperature with NMR that sets superconducting properties. Based on these findings, combined with new insight from high-pressure NMR data it is shown that these local charges vary spatially in the CuO$_2$ plane. In fact, it will be argued that charge density variations in the cuprates are ubiquitous. [Preview Abstract] |
Wednesday, March 15, 2017 9:36AM - 9:48AM |
K41.00009: Comparing the spin structure factor between parent compounds in different cuprate families Brian Moritz, Yao Wang, Edwin Huang, Chunjing Jia, Thomas P. Devereaux Understanding differences in the magnetic excitation spectra between parent compounds of various cuprate families can provide insight on differences in each family’s temperature-doping phase diagram. Using small cluster exact diagonalization and numerically exact determinant quantum Monte Carlo, we evaluate the spin structure factor of the Hubbard model, accounting for model parameter variations between each family. We compare our results to recent resonant inelastic x-ray scattering measurements and comment on important controlling parameters. [Preview Abstract] |
Wednesday, March 15, 2017 9:48AM - 10:00AM |
K41.00010: Electronic structure of CuTeO$_4$ and its relationship to cuprates Michael Norman, Antia Botana Based on first principles calculations, the electronic structure of CuTeO$_4$ is discussed in the context of superconducting cuprates. Despite some significant crystallographic differences, we find that CuTeO$_4$ is similar to these cuprates, exhibiting a quasi two dimensional electronic structure that involves hybridized Cu-$d$ and O-$p$ states in the vicinity of the Fermi level, along with an antiferromagnetic insulating ground state. Hole doping this material by substituting Te$^{6+}$ with Sb$^{5+}$ would be of significant interest. [Preview Abstract] |
Wednesday, March 15, 2017 10:00AM - 10:12AM |
K41.00011: Robustness of the insulating band structure of BaBiO3 films in the ultrathin limit Muntaser Naamneh, Dariusz Gawryluk, Tian Shang, Daniel McNally, Joël Mesot, Ming Shi, Milan Radovic, Nicholas Plumb BaBiO3 is a fully-gapped charge density wave (CDW) insulator at all temperatures, due to a 3D static breathing distortion of the BiO6 octahedra -- essentially a frozen lattice of polarons. With hole doping, it becomes a 30 K superconductor. At the same time, the static distortions vanish, though fluctuations could conceivably persist and play a role in superconductivity. Hence, trying to perturb the CDW order is an appealing route to gain new insights into the nature of the unusual insulating phase and the interactions at play in bismuthate high-Tc superconductivity. With this in mind, we have performed ARPES on BaBiO3 films as a function of thickness. The measured band structure shows that BaBiO3 can remain crystalline and insulating down to surprisingly low thickness, where one might otherwise have expected a breakdown of the 3D CDW. The results give a new perspective on the relative influence of long-range Peierls interactions and short-range ``bond disproportionation'' phenomena in this class of materials. [Preview Abstract] |
Wednesday, March 15, 2017 10:12AM - 10:24AM |
K41.00012: Power-law liquids in the cuprates from unparticle interactions Zhidong Leong, Kridsanaphong Limtragool, Chandan Setty, Philip Phillips Recent photoemission measurements of the cuprates reveal that, over a wide range of doping levels, scattering rates along the nodal direction exhibit power-law scaling as a function of frequency and temperature. We show that these observations can be qualitatively reproduced by considering interactions between electrons and unparticles --- a low-energy scale-invariant sector that emerges from integrating out the high-energy degrees of freedom. We perturbatively evaluate the electron self-energy $\Sigma$ due to interactions with both fermionic and bosonic unparticles. We find that, at low temperatures, Im$\Sigma$ exhibits the same power law in both temperature and frequency, with the exponent depending on the scaling dimension of the unparticle propagator. At high temperatures, Im$\Sigma$ is linear in temperature. We attribute these non-Fermi-liquid behaviors to the incoherent component of the unparticle propagator. We find that this incoherent nature also violates the sum rules for the density of states and the density-density correlation function. Such violations can, in principle, be observed experimentally. Our work indicates that power-law scaling in the cuprates originates from the incoherent background generated from Mott-scale physics. [Preview Abstract] |
Wednesday, March 15, 2017 10:24AM - 10:36AM |
K41.00013: States induced in the single-particle spectrum by infinitesimal doping of a Mott insulator Masanori Kohno Doping a Mott insulator induces states in the Mott gap in the single-particle spectrum. The general relationships between the doping-induced states in the small-doping limit and the magnetically excited states of the Mott insulator are clarified by considering the quantum numbers and the overlaps between the states [1]. By using the $t$-$J$ ladder model, the characteristic features of the doping-induced states in the small-doping limit are concretely demonstrated [1]. The features imply that the Mott transition is characterized by freezing of the charge degrees of freedom while the spin degrees of freedom remain active, which is consistent with the results for the Mott transition in the one- and two-dimensional Hubbard and $t$-$J$ models [2--5]. [1] M. Kohno, Phys. Rev. B 92, 085129 (2015). [2] M. Kohno, Phys. Rev. Lett. 105, 106402 (2010). [3] M. Kohno, Phys. Rev. Lett. 108, 076401 (2012). [4] M. Kohno, Phys. Rev. B 92, 085128 (2015). [5] M. Kohno, Phys. Procedia 75, 206 (2015). [Preview Abstract] |
Wednesday, March 15, 2017 10:36AM - 10:48AM |
K41.00014: Analytical study of orbital selective Mott transition using slave-spin method Yashar Komijani, Gabriel Kotliar We study the orbital selective Mott transition using slave-spin and slave-boson techniques. Within a single-site approximation, we identify the competing ground states of the spin-sector of a two-band Hubbard Hamiltonian in presence of the Hund’s rule coupling as well as inter-orbital tunneling and provide an analytical explanation for the orbital correlation (mode locking) and Kondo physics. By mapping the lattice to the impurity model we make connections to the dynamical mean-field theory. [Preview Abstract] |
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