Bulletin of the American Physical Society
APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016; Baltimore, Maryland
Session K8: Superconductivity: Cuprates |
Hide Abstracts |
Sponsoring Units: DCMP Room: 304 |
Wednesday, March 16, 2016 8:00AM - 8:12AM |
K8.00001: FERMIOLOGY OF THE UNDOPED CUPRATE SUPERCONDUCTOR Pr$_{\mathrm{2}}$CuO$_{\mathrm{4}}$ Ross McDonald, Nicholas Breznay, Yoshiharu Krockenberger, Kimberly MODIC, Zengwei Zhu, Ian Hayes, Nityan Nair, Toni Helm, Hiroshi Irie, Hideki Yamamoto, James Analytis Unconventional, high temperature superconductivity consistently appears in the vicinity of suppressed phase transitions, leading to the suggestion that quantum criticality is vital to the physics of these systems. A confounding factor in identifying the role of quantum criticality in the electron-doped cuprates is the competing influence of chemical doping and oxygen stoichiometry. Recent advances in molecular beam epitaxy and preparation of cuprate thin films indicate that annealing can be employed to optimize Tc via the control of apical oxygen occupancy. For Pr$_{\mathrm{2}}$CuO$_{\mathrm{4\pm \delta \thinspace }}$the resulting square planar coordinated structure exhibits a 25 K superconducting transition in the absence of Cerium doping. Using these films and ultra high magnetic fields (\textgreater 90 T) enables measurements of magnetic quantum oscillations -- the first observation of their kind for a cuprate thin film. The oscillation frequency is consistent with the reconstructed Fermi surface of the bulk electron-doped cuprate Nd$_{\mathrm{2-x}}$Ce$_{\mathrm{x}}$CuO$_{\mathrm{4}}$. Furthermore, we observe a mass enhancement, suggesting that tuning these materials via oxygen stoichiometry enables exploration of underlying quantum criticality, providing a new axis with which to explore the physics underlying the electron doped side of the cuprate phase diagram. [Preview Abstract] |
Wednesday, March 16, 2016 8:12AM - 8:24AM |
K8.00002: Single reconstructed Fermi surface pocket in an underdoped single layer cuprate superconductor Mun K. Chan, R. D. McDonald, B. J. Ramshaw, K. A. Modic, N. Barisic, M. Greven, N. Harrison The observation of a small reconstructed Fermi surface with quantum oscillations in bilayer YBa$_{\mathrm{2}}$Cu$_{\mathrm{3}}$O$_{\mathrm{6+x}}$ opened a path towards identifying broken symmetry states in underdoped cuprates. However, the multi-frequency spectrum of quantum oscillations and complications from bilayer coupling has rendered such an identification inconclusive. Our high resolution quantum oscillation study of the structurally simpler single layer cuprate HgBa$_{\mathrm{2}}$CuO$_{\mathrm{4+\delta }}$ (Hg1201) reveal a single oscillatory component with no signatures of magnetic breakdown tunneling. From this, we conclude that the reconstructed Fermi surface of Hg1201 is comprised of only a single pocket with negligible c-axis warping. Quantitative modeling of these results allow us to determine that biaxial charge-density-wave order is responsible for Fermi surface reconstruction. We find that the characteristic reconstruction gap is a significant fraction of the pseudogap energy. `Criss-crossed' uniaxial charge stripes is ruled out as a viable alternative to biaxial order within a CuO$_{\mathrm{2}}$ plane for Hg1201. [Preview Abstract] |
Wednesday, March 16, 2016 8:24AM - 8:36AM |
K8.00003: Crystal Growth and Electronic Raman Scattering Study of Model High-Tc Cuprate HgBa2CaCu2O6$+$\textbrokenbar \"{A} Lichen Wang, Yuan Li, Xiangpeng Luo, Jiarui Li In this talk, I will report our recent progress on crystal growth of HgBa2CaCu2O6$+$x (Hg1212), which possesses a simple tetragonal crystal structure and the highest ambient-pressure Tc (128 K) among all cuprate superconductors with two CuO2 sheets in the primitive cell. Improvement in single-crystal synthesis was made possible by using self-designed high-pressure furnaces and a two-layer encapsulation method, and we demonstrate that the hole concentration can be homogeneously tuned in the underdoped region by post-growth annealing. Our electronic Raman scattering experiments reveal that the maximum of the d-wave superconducting gap increases from single-layer HgBa2CuO4$+$x to double-layer Hg1212. In the same spectra, it is found that the characteristic energy of spin excitations, as manifested by the energy of the two-magnon signal, also increases in a nearly proportional fashion. This result is consistent with the idea that magnetic interactions are closely related to the Cooper pairing mechanism. [Preview Abstract] |
Wednesday, March 16, 2016 8:36AM - 8:48AM |
K8.00004: Effects of pressure and disorder on superconductivity in Tl$_{\mathrm{2}}$Ba$_{\mathrm{2}}$Ca$_{\mathrm{n-1}}$Cu$_{\mathrm{n}}$O$_{\mathrm{2n+4+\delta \thinspace }}$(n$=$2,3) Jian-Bo Zhang, Xiao-Jia Chen, Viktor Struzhkin, Wenge Yang, Ho-Kwang Mao, Hai-Qing Lin, Yong-Chang Ma, Nan-Lin Wang The structural, vibrational, and superconducting properties of nearly optimally doped Tl$_{\mathrm{2}}$Ba$_{\mathrm{2}}$Ca$_{\mathrm{n-1}}$Cu$_{\mathrm{n}}$O$_{\mathrm{2n+4+\delta }}$ (n$=$2,3) single crystals are~studied~at high pressures. While the superconducting transition temperature $T_{\mathrm{c}}$ of the bilayer system exhibits a parabolic behavior with a maximum around an optimal pressure level, its increased path has a kink in the trilayer compound, indicating a joint effect from the inner CuO$_{\mathrm{2}}$ plane. The latter is further supported by the appearance of the two additional Raman modes. At higher pressures, we observe the sudden increase of the full width at half maximum of some lattice modes as well as the anomaly of the lattice parameters at certain pressure. These together contribute the enhanced disorder and the~$T_{\mathrm{c}}$ reduction accordingly. We thus are able to distinguish the contribution to $T_{\mathrm{c}}$ from the intrinsic pressure variables, disorder, and the CuO$_{\mathrm{2}}$ plane number and type in this layered family. [Preview Abstract] |
Wednesday, March 16, 2016 8:48AM - 9:00AM |
K8.00005: Bulk superconductivity at 84 K in the strongly overdoped regime of cuprates Andrea Gauzzi, Yannick Klein, Elvezio Morenzoni, Mikko Nisula, Maarit Karppinen, Massimo Marezio, Theodore H. Geballe By means of magnetic susceptibility, specific heat and muon-spin relaxation ($\mu$SR) measurements, we report on bulk superconductivity at 84 K in high-pressure oxidized Cu$_{0.75}$Mo$_{0.25}$Sr$_2$YCu$_2$O$_{7.54}$. A record short apical Cu-O distance and a large excess of electronic specific heat at low temperature give evidence of hole overdoping, $p \approx 0.43$ hole/Cu, well beyond the superconducting dome relating $T_c$ and $p$, considered universally valid for cuprates, where a normal Fermi liquid behavior is expected. On the other hand, the superfluid density measured by means of $\mu$SR is similar to that of optimally doped YBa$_2$Cu$_3$O$_{7-\delta}$, which indicates that the extra-holes do not contribute to superconductivity, thus leading to a phase separation between superconducting and normal carriers, or that Cooper pairs are strongly localized. In both cases, the unexpected observation of high $T_c$ in the strongly overdoped regime constitutes a further open issue for the theoretical explanation of superconductivity in cuprates. [Preview Abstract] |
(Author Not Attending)
|
K8.00006: Enhanced Surface Superconductivity in Single Crystal La$_{2-x}$Ba$_x$CuO$_4$ Ivar Martin, Xian Yang Tee, Toshimitsu Ito, Tomoharu Ushiyama, Yasuhide Tomioka, Christos Panagopoulos Surfaces of materials often possess properties which are distinctly different from their bulk. The atomic structure can develop intricate new patterns due to surface reconstruction and the electronic properties can be very distinct, as most dramatically manifested in topological insulators. However, more subtle collective phenomena such as superconductivity are not as strongly affected by the presence of surfaces. Here, we report an unprecedented finding of enhanced superconductivity at the ab-plane surface of high-$T_c$ cuprate La$_{2-x}$Ba$_x$CuO$_4$. Spatially-resolved electrical and thermoelectric transport measurements detect a superconducting surface below the transition temperature $T_{cs}$ which is considerably higher than the bulk $T_c$. The effect is pronounced in the region of charge carrier doping ($x$) with strong spin-charge stripe correlations. Notably, for $x = 0.12$, $T_{cs}$ reaches 36 K, exceeding even the highest reported bulk $T_c$ in this material for any doping. Possible interpretations for the novel effect are discussed. [Preview Abstract] |
Wednesday, March 16, 2016 9:12AM - 9:24AM |
K8.00007: Vortex Lattice Formation in High Magnetic Fields in an Underdoped Single Crystal of Hg1201 from $^{17}$O NMR Jeongseop Lee, Yizhou Xin, W. P. Halperin, A. P. Reyes, P. L. Kuhns The vortex lattice in HgBa$_{2}$CuO$_{4+\delta}$ forms at a vortex melting temperature, T$_{v}$, typically $\sim$40K for underdoped crystals with a hole doping $\sim$ 0.11. We present our results from $^{17}$O NMR for investigation of the vortex lattice as a function of external magnetic field up to 30 T and temperature as low as 5 K. The vortex contribution to the NMR linewidth can be separated from inhomogeneous broadening by deconvolution of the normal state spectra which was measured separately above, T$_{v}$. The vortex melting temperature was measured for two underdoped samples marked by the onset of extra linewidth broadening due to the inhomogeneous magnetic field distribution from the solid vortex lattice consistent with transverse relaxation measurements. We have found evidence for a change in the vortex lattice symmetry as a function of external fields. This work was supported by the DOE BES under grant No. DE-FG02-05ER46248 and the NHMFL through the NSF and State of Florida. \noindent [1] V. F. Mitrovic, {\it et al.}, Nature, {\bf 413}, 501-504 (2001).\\ \noindent [Preview Abstract] |
Wednesday, March 16, 2016 9:24AM - 9:36AM |
K8.00008: Broken bond symmetry assists stripe pinning in superconducting La$_{2-x}$Sr$_x$CuO$_4$ John Tranquada, H. Jacobsen, I.A. Zaliznyak, M. Huecker, G.D. Gu, A.T. Savici, B. Winn, S. Chang There has been evidence for quite some time for some degree of charge and spin stripe order in La$_{2-x}$Sr$_x$CuO$_4$ (LSCO). This has been a bit surprising as the crystal structure is supposed to lack the anisotropic Cu-O bonds that lead to robust stripe pinning in La$_{2-x}$Ba$_x$CuO$_4$. Using neutron scattering measurements on the HYSPEC instrument at the Spallation Neutron Source, we have discovered evidence for broken bond symmetry and strong associated lattice fluctuations in an LSCO crystal with $x=0.07$ [1]. The broken bond symmetry occurs within the orthorhombic phase. We also observe quasielastic incommensurate spin excitations that coexist with the bulk superconductivity, suggesting some degree of pair-density-wave order in the superconducting state. \par\noindent [1] H. Jacobsen {\it et al.}, Phys. Rev. B (accepted); arXiv:1508.02429. [Preview Abstract] |
Wednesday, March 16, 2016 9:36AM - 9:48AM |
K8.00009: Neutron scattering study of the antiferromagnetic response of HgBa$_{\mathrm{2}}$CuO$_{\mathrm{4+\delta }}$ Yang Tang, Mun Chan, Chelsey Dorow, Mike Veit, Yang Ge, Martin Greven, Lucile Mangin-Thro, Yvan Sidis, Philippe Bourges, Xudong Zhao, Paul Steffens, Andrew Christianson, Douglas Abernathy, Jitae Park Antiferromagnetic correlations have been argued to be the cause of the $d$-wave superconductivity and of the pseudogap phenomena exhibited by the cuprates. Although neutron scattering experiments of the antiferromagnetic response have been reported for a number of cuprates, results for structurally simple HgBa$_{\mathrm{2}}$CuO$_{\mathrm{4+\delta }}$ (Hg1201) have begun to emerge only recently. Specifically, we have found for moderately-doped Hg1201 ($T$c $\approx $ 71 K, pseudogap temperature $T$* $\approx $ 305 K) that the two most prominent features of the magnetic spectrum reported for other cuprates are absent: the X-shaped `hourglass' response and the resonance mode in the superconducting state. Instead, the response of Hg1201 is Y-shaped, gapped, and significantly enhanced below $T$* [1]. Here we will discuss our ongoing efforts to understand the doping dependence of the AF response in Hg1201. [1] M. K. Chan \textit{et al., }arXiv:1402.4517. [Preview Abstract] |
Wednesday, March 16, 2016 9:48AM - 10:00AM |
K8.00010: Dynamics of quasiparticles and antiferromagnetic correlations in electron-doped cuprate La$_{2-x}$Ce$_x$CuO$_{4\pm\delta}$ (LCCO) I. M. Vishik, F. Mahmood, Z. Alpichshev, J. S. Higgins, R. L. Greene, N. Gedik We studied quasiparticle dynamics in thin films of the electron-doped cuprate La$_{2-x}$Ce$_x$CuO$_4$ (LCCO) via optical pump-probe spectroscopy. In underdoped LCCO, the quasiparticle recombination dynamics imply a nodeless superconducting gap, which can be realized with d$_{x^2-y^2}$ symmetry if a nodal hole-pocket is absent. Meanwhile, optimally doped LCCO shows recombination dynamics consistent with line nodes. Above T$_c$, fluence-dependent dynamics indicate a fully-formed gap in the density of states, which is associated with antiferromagnetic correlations, and limits can be placed on the correlation length and time. [Preview Abstract] |
Wednesday, March 16, 2016 10:00AM - 10:12AM |
K8.00011: A close look at antiferromagnetic phase boundary in multidimensional phase diagram of electron-doped copper oxide Heshan Yu, Ge He, Ziquan Lin, Jie Yuan, Beiyi Zhu, Yi-feng Yang, Tao Xiang, Feo.V. Kusmartsev, Liang Li, Junfeng Wang, Kui Jin In copper-oxide superconductors, spin fluctuations play a predominant role in electron pairing with electron dopants yet composite orders veil the nature of superconductivity for hole-doped family. However, in electron-doped ones the ending point of AFM is still in controversy for different probes or its sensitivity to oxygen content. Here, by carefully tuning the oxygen content, a systematic study of Hall signal and magnetoresistivity up to 58 Tesla on optimally doped La$_{2-x}$Ce$_{x}$CuO$_{4\pm \delta }$ (x $=$ 0.10) thin films identifies two characteristic temperatures at 62.5 K (error is 7.5 K) and 25 K (error is 5 K). The former is quite robust whereas the latter becomes flexible with increasing magnetic field, thereby linked to two- and three-dimensional AFM, evident from the multidimensional phase diagram as a function of oxygen as well as Ce dopants. Consequently, the observation of extended AFM phase in contrast to $\mu $SR probe corroborates an elevated critical doping in field, providing an unambiguous picture to understand the interactions between AFM and superconductivity. [Preview Abstract] |
Wednesday, March 16, 2016 10:12AM - 10:24AM |
K8.00012: Superconductivity and planar hole densities in the cuprates from NMR Juergen Haase, Michael Jurkutat, Damian Rybicki We show how nuclear magnetic resonance (NMR) of $^{63}$Cu and $^{17}$O provides a quantitative measure of the charge distribution in the ubiquitous CuO$_2$ plane, the common structural feature of cuprate physics. The various materials are found to differ significantly in the local charge distribution, while the total charge per CuO$_2$ matches expectation from stoichiometry. Using the local charges on Cu and O measured by NMR, a new three-dimensional cuprate phase diagram is drawn that consistently encompasses all cuprate materials. These appear ordered according to their maximum $T_{\rm c}$. It is the sharing of the inherent Cu hole with O that sets an upper limit for $T_{\rm c}$, and it correlates with the superfluid density measured by $\mu$SR, over all cuprate families. [Preview Abstract] |
Wednesday, March 16, 2016 10:24AM - 10:36AM |
K8.00013: Change of carrier density at the pseudogap critical point of a cuprate superconductor Louis Taillefer, Sven Badoux, Gael Grissonnanche, Nicolas Doiron-Leyraud, Wojciech Tabis, Francis Laliberte, Baptiste Vignolle, David Vignolles, Jerome Beard, Cyril Proust, Doug Bonn, Ruixing Liang, Walter Hardy The pseudogap is a central puzzle of cuprate superconductors. Its connection to the Mott insulator at low doping $p$ remains ambiguous and its relation to the charge order that reconstructs the Fermi surface at intermediate $p$ is still unclear. Here we use measurements of the Hall coefficient in magnetic fields up to 88~T to show that Fermi-surface reconstruction by charge order in YBa$_2$Cu$_3$O$_y$ ends sharply at a critical doping $p = 0.16$, distinctly lower than the pseudogap critical point at $p^\star = 0.19$. This shows that pseudogap and charge order are separate phenomena. We then find that the change of carrier density from $n = 1 + p$ in the conventional metal at high $p$ to $n = p$ in the lightly doped regime at low $p$ starts at $p^\star$. This shows that pseudogap and antiferromagnetic Mott insulator are linked. [Preview Abstract] |
Wednesday, March 16, 2016 10:36AM - 10:48AM |
K8.00014: Charge order and the pseudogap in the underdoped cuprates: a quantum oscillation study Yu-Te Hsu, Mate Hartstein, Neil Harrison, Mun Chan, Kimberly Modic, Juan Porras, Toshinao Loew, Mathieu Le Tacon, Bernhard Keimer, Suchitra Sebastian I will present quantum oscillation results on the underdoped copper-oxide superconductors to address the question of the interplay of the charge ordered ground state with the pseudogap. Specifically we experimentally distinguish between the two cases where charge order reconstructs a large paramagnetic Fermi surface predicted by band structure, or where charge order reconstructs a truncated Fermi surface where the density of states is restricted to the nodal region, as observed in the pseudogap state. [Preview Abstract] |
Wednesday, March 16, 2016 10:48AM - 11:00AM |
K8.00015: Anomalous suppression of energy gap near the antinode in Bi2212 Alfred Zong, Sudi Chen, Yu He, Makoto Hashimoto, Shigeyuki Ishida, Yoshiyuki Yoshida, Zhi-Xun Shen An energy gap holds special importance in the study of high-$T_c$ superconductors (HTSC) as it is often associated with the order parameter of complex phases in these materials. In hole-doped cuprates around optimal doping, past experiments suggest the presence of two momentum-anisotropic energy gaps originating from $d$-wave superconductivity and pseudogap. Here we report an anomalous energy gap suppression near the antinode in overdoped Bi2212 that persists from $T \ll T_c$ to $T > T_c$. Our data imply that the suppression may not originate from pair-breaking scattering, but can be phenomenologically described by higher harmonics of a $d$-wave gap. It is important to uncover the origin of this suppression, which is instrumental in understanding the complex landscape of interacting order parameters in cuprate HTSCs. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700