Bulletin of the American Physical Society
APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011; Dallas, Texas
Session T23: Focus Session: Search for New Superconductors III: Reduced Dimensionality |
Hide Abstracts |
Sponsoring Units: DMP Chair: Ray Baughman, University of Texas at Dallas Room: D165 |
Wednesday, March 23, 2011 2:30PM - 3:06PM |
T23.00001: Understanding anisotropy to develop superconducting design principles Invited Speaker: Superconductivity is often found in families of compounds which share a common building block (e.g. CuO$_{2}$ planes in cuprates, FeAs planes in pnictides, and CeIn$_{3}$ planes in a subset of heavy fermion superconductors). This fact provides a rationale to search for new superconductors, and subsequently a means to try and understand the origin of superconductivity by examining trends in superconducting behavior within a family of superconductors which hopefully transcends any one particular family of compounds. The notion of common building blocks has led us to the recent discovery of superconductivity at 2.1 K in CePt$_{2}$In$_{7}$, coexisting magnetism and superconductivity in PuCoIn$_{5}$, and a correlated paramagnet in PuPt$_{2}$In$_{7}$. I will discuss our attempts to understand the role of reduced dimensionality and increased bandwidth within the ``115'' class of heavy fermion superconductors by examining trends in the charge and spin degrees of freedom that are correlated with superconductivity. In this way, we aim to lay the foundation for a modern, microscopic version of Matthias' rules for unconventional superconductivity from which superconducting design principles can be developed. In collaboration with Eric Bauer, Jianxin Zhu, Paul Tobash, Moaz Altarawneh, HB Rhee, Hironori Sakai, Kris Gofryk, Neil Harrison, and Joe Thompson. [Preview Abstract] |
Wednesday, March 23, 2011 3:06PM - 3:18PM |
T23.00002: PuCoIn$_{5}$: A New Magnetic Superconductor Eric D. Bauer, J.N. Mitchell, P.H. Tobash, F. Ronning, J.-X. Zhu, B.L. Scott, J.D. Thompson There is renewed interest in actinide research following the discovery of superconductivity at T$_{c}$=18.5 K in PuCoGa$_{5}$ and at T$_{c}$=8.7 K in PuRhGa$_{5}$. These materials appear to be unconventional superconductors with a moderate effective mass enhancement and are similar to the more well characterized CeMIn$_{5}$ (M=Co, Rh, Ir) superconductors. We have discovered a new member of this ``115'' family of superconductors, PuCoIn$_{5}$. This material superconducts at T$_{c}$=2.7 K and exhibits another phase transition at T$_{N}$=15 K, likely due to antiferromagnetic order. The Sommerfeld coefficient $\gamma $ = 200 mJ/mol K$^{2}$ and the large initial slope of the upper critical field indicate a large enhancement of the effective mass. The physical properties of PuCoIn$_{5}$ will be discussed. [Preview Abstract] |
Wednesday, March 23, 2011 3:18PM - 3:30PM |
T23.00003: Search for Superconductivity in Carbon Nanotubes Doped by Boron Ion Implantation Nicholas Cornell, Alex Kutsenov, Austin Howard, Nathaniel Mayo, Eduard Galstayan, Wei Kan Chu, Herbert Freyhardt, Anvar Zakhidov, Xuemei Wang The boron doping of single wall carbon nanotubes(CNT) by laser ablation synthesis has been reported to create superconducting B-CNTs with Tc's ranging from 12-19 Kelvin, depending on CNT inter-tube connection strength. We attempt to create boron doped multiwall CNT by ion implantation doping. Ion doping of boron(B) was performed at 60keV and 20keV, and low temperature transport combined with SQUID and ESR/LFMA was used in searching for SC. We have found that R(T) strongly depends on the metallic contact geometry. With thin film contacts on CNT sheets the R(T) shows no SC signatures, while when an Ag or Au paste penetrates the highly porous network of B doped multiwall CNT then R(T) drops and curvature changes are observed resembling SC transitions with Tc depending on B concentration and metallic electrode distances. We discuss these results in terms of possible SC in hybride ``metal-CNT'' system in which metal was predicted to supress phase fluctuation in one dimensional CNT network [1]. \\[4pt] [1] Erez Berg, Dror Orgad, and Steven A. Kivelson, Phys. Rev. B 78, 094509(2008) [Preview Abstract] |
Wednesday, March 23, 2011 3:30PM - 3:42PM |
T23.00004: Low Field Microwave Absorption Studies of Carbon Nanotubes Doped by Chemical and Ion Implantation Techniques Austin Howard, Alexander Kuznetsov, Nicholas Cornell, Myron Salamon, Eduard Galstayan, Wei Kan Chu, Herbert Freyhardt, Ray Baughman, Junji Haruyama, Jason Reppert, Apparao Rao, Anvar Zakhidov The motivation of this study is to develop a highly sensitive method of microwave absorption in low magnetic fields (LFMA), combined with SQUID magnetometry and resistivity, for searching for superconducting phases in in-situ doped nanomaterials; either chemically (by alkali metals or metalloids) or through Boron ion implantation. These methods have been applied to both MWNTs grown by CVD, as well as SWNTs which have been separated into metallic and semiconducting chiralities. Regardless of the doping technique or element, we have found a much higher rate of doping in the semiconducting SWNTs. Additionally, in the Boron doped SWNTs, we see two transitions at $\sim$8 K and $\sim$30 K, but the nature of the transition is not clear at the moment: it depends on the type of measurement. While SQUID and resistivity indicate a superconducting type transition, LFMA/ESR reveals that there is a clear magnetic transition at 30 K. Resolution of these differing results will be discussed. [Preview Abstract] |
Wednesday, March 23, 2011 3:42PM - 3:54PM |
T23.00005: Electric Field Induced Superconductivity in Layered Materials J.T. Ye, M.F. Craciun, S. Russo, M.F. Morpurgo, Y. Kasahara, H.T. Yuan, H. Shimotani, Y. Iwasa Using electric double layer (EDL) gating, large amount of carriers can be accumulated on a broad range of materials, which provides new opportunities in effectively manipulating their electronic properties in complementary with the chemical doping. In searching for novel transport phenomena, layered materials are advantageous because atomically flat surface can be easily fabricated using the graphene techniques. We used layered material: ZrNCl and graphite to act as the channel of EDL transistors. For both ZrNCl and graphene, we achieved high carrier density up to 10$^{14}$ cm$^{-2}$, electrostatically. For graphene, we studied the high carrier density transport for graphene of 1-3 layers. Transport properties at the high carrier density exhibit clear layer dependence governed by the intrinsic band structures of graphene and its multi-layers. For ZrNCl EDL transistor, we observed metallic states at gate voltage higher than 3.5 V followed by gate-induced superconductivity after metal-insulator transition when the transistor was cooled down to about 15 K. [Preview Abstract] |
Wednesday, March 23, 2011 3:54PM - 4:06PM |
T23.00006: Electric Double Layer Charging on Graphene Feng Chen, Bing Lv, Yuyi Xue, C.W. Chu, Howard Wang Electric Double Layer (EDL) charging as a new charging method has attracted wide interests recently. We have employed this method to graphene and obtained an estimated surface charge density of 4$\times 10^{15}$ electrons/cm$^2$. The resistance dropped significantly upon charging and the physical properties under various charging conditions were studied. We will present these along with results of the EDL charging on other superconducting candidates. [Preview Abstract] |
Wednesday, March 23, 2011 4:06PM - 4:18PM |
T23.00007: Search for new superconductors in the La-Si-C system Jose De la Venta, Ali C. Basaran, Ted Grant, Antonio Jefferson S. Machado, Zachary Fisk, Ivan K. Schuller We have searched for the presence of superconductivity in the La-Si-C system in bulk and thin film samples. This system has some of the common features that are present in high T$_{C}$ superconducting materials. It is a multi-element compound and also incorporates a light element, Carbon. Furthermore, one of the binary phases, La$_{5}$Si$_{3}$ exhibits a tetragonal layered structure. This system exhibits the presence of a possible new superconducting compound with T$_{C}$'s ranging from 6.1 K to 8.5 K. In the binary La-Si system there are five inter-metallic phases. Among these phases, those that exhibit superconductivity are: LaSi$_{2}$ with T$_{C}$ of 2.3 K, La$_{3}$Si$_{2}$ with a T$_{C}$ of 2.1 K and La$_{5}$Si$_{3}$ with a T$_{C}$ of 1.6 K. A careful analysis of several physical properties (SQUID, Modulated Microwave Absorption) and x-ray powder diffraction, (using Rietveld refinement) shows that superconductivity in this system could be ascribed to intermediate binary (La$_{2}$C$_{3})$ and single (La-\textit{$\beta $}) phases of the system. [Preview Abstract] |
Wednesday, March 23, 2011 4:18PM - 4:30PM |
T23.00008: Superconducting properties of quasi-one dimensional graphene George Karakonstantakis, Steve Kivelson We study quasi-one dimensional graphene (polyacene) two leg ladders modeled by repulsive U Hubbard model using DMRG. The strong repulsive interactions along with the high density of states at the Fermi energy enhance the conducting properties of the ladder (which is a conductor) and give rise to enhancement of the pairing energy scales, having to do with the superconducting properties of the ladder. The presence of phonons in this system has been known to give rise to Peierls ans superconducting instabilities as well. [Preview Abstract] |
Wednesday, March 23, 2011 4:30PM - 4:42PM |
T23.00009: Unusual Superconductivity in the Homologous Series (Cu$_{0.75}$Mo$_{0.25})$Sr$_{2}$(Ce,Y)$_{s}$Cu$_{2}$O$_{5+2s+\delta }$ Omar Chmaissem, Inga Grigoraviciute, Maarit Karppinen, Hisao Yamauchi, Massimo Marezio The structures and bulk superconductivity ($>$30{\%} Meissner volume fraction) of the first four members of the high-$T_{c}$ series (Cu$_{0.75}$Mo$_{0.25})$Sr$_{2}$(Ce,Y)$_{s}$Cu$_{2}$O$_{5+2s+\delta }$have been successfully determined. Partial Mo substitution for Cu in the square-chains enhances $T_{c}$ to 87 K (for $s $= 1) and leads to significant oxygen loading capabilities well beyond the levels achieved in typical YSr$_{2}$Cu$_{3}$O$_{6+\delta }$, YBa$_{2}$Cu$_{3}$O$_{6+\delta }$, and other similar cuprates. Higher members of the series have their adjacent superconducting CuO$_{2}$ layers separated by increasingly thicker fluorite-like (Ce,Y)$_{2}$O$_{2}$ insulating blocks. Insertion of two or more of these blocks must drastically affect the CuO$_{2}$ interlayer coupling and causes $T_{c}$ to immediately drop and saturate at $\sim $57 K ($s$ = 2-4). The infinite chains of Cu-centered squares in YBCO change to alternate chains of mixed Cu squares and Cu and Mo octahedra. Neutron diffraction confirms the formation of reservoir blocks with a new structure and stoichiometry and of a surprisingly large Cu oxidation state of $\sim $2.5+, suggesting the possibility of an unusual superconducting pairing mechanism. [Preview Abstract] |
Wednesday, March 23, 2011 4:42PM - 4:54PM |
T23.00010: Electrical Transport Properties of Boron-Based Nanostructures Joel D. Chudow, Daniel F. Santavicca, Luigi Frunzio, Daniel E. Prober, Michael Rooks, Eswaramoorthi Iyyamperumal, Gayatri Keskar, Fang Fang, Lisa Pfefferle Many metal boride materials exhibit interesting electrical properties. Bulk MgB$_{2}$ has a superconducting transition temperature of 39 K. Boron-based nanostructures are predicted to possess special properties superior to those of other one-dimensional nanomaterials. Recent progress in material fabrication has enabled the successful synthesis of boron-based nanomaterials [J. Phys. Chem. C 113, 17661 (2009)]. Magnetization measurements of magnesium-boride nanostructures show evidence of a diamagnetic transition at high temperature, about 80 K. We describe electrical transport measurements of individual single nanowires composed of these and related materials. [Preview Abstract] |
Wednesday, March 23, 2011 4:54PM - 5:06PM |
T23.00011: Structure and electronic properties of the La$_{4}$Ni$_{3}$O$_{8}$ Konstantin Lokshin, Takeshi Egami The Ni$^{1+}$/Ni$^{2+}$ states of nickelates have the identical (3$d^{9}$/3$d^{8})$ electronic configuration as Cu$^{2+}$/Cu$^{3+}$ in the high temperature superconducting cuprates, and are expected to show interesting properties. However, La$_{4}$Ni$_{3}$O$_{8}$, has infinite NiO$_{2}$ layers with Ni valence 1.33 and demonstrate a magnetic transition at 105 K, which has not been explained unambiguously yet. Here we report X-rays and Neutron diffraction evidences clarifying the nature of the transition. The observed structural changes around 105 K suggest that the magnetic transision in La$_{4}$Ni$_{3}$O$_{8}$ originates from Yahn Teller effect that accompanies with high spin -- low spin transition. Thus, at low temperature the structural motive, electronic configuration and the spin state of Ni$^{1+}$/Ni$^{2+}$ nickelates are identical to Cu$^{2+}$/Cu$^{3+}$ cuprates. [Preview Abstract] |
Wednesday, March 23, 2011 5:06PM - 5:18PM |
T23.00012: Transport and Spectroscopy Studies of Ultrathin Doped Nickelate Films Yaron Segal, Joseph Ngai, Divine Kumah, Ankit Disa, James Reiner, Jarret Moyer, Dario Arena, Fred Walker, Charles Ahn The notion of a rational, first-principles based design of a novel superconducting material has intrigued physicists for decades. Recently it was suggested that by enforcing a two- dimensional confinement and tensile strain on LaNiO$_{3}$ films, their electronic structure can be made sufficiently similar to that of the Mott-Hubbard system in the cuprates, possibly inducing an antiferromagnetic insulator-superconductor transition [PRL 100, 016404]. We adopt this approach through the synthesis of ultrathin La$_{x}$Nd$_{1-x}$NiO$_{3}$ and hole-doped La$_{x}$Ba$_{1- x}$NiO$_{3}$, Nd$_{x}$Ba$_{1-x}$NiO$_{3}$ films using molecular beam epitaxy. High structural quality is demonstrated by RHEED oscillations and synchrotron x-ray diffraction. Transport measurement show a transition from metallic behavior to localization for films less than 8 uc thick. Tuning of the La/Nd ratio allows the film to be driven into the antiferromagnetic insulating regime. Surprisingly, Ba incorporation increases the localization in the films, which is in contrast to the metallicity-promoting effect of hole doping in bulk nickelates. X-ray absorption measurements allow us to follow the evolution of the Ni and O orbitals and relate it to the observed transport properties. [Preview Abstract] |
Wednesday, March 23, 2011 5:18PM - 5:30PM |
T23.00013: Superconductivity at 7.7 K in new hexagonal bronze Hg$_{x}$ReO$_{3}$ Kenya Ohgushi, Ayako Yamamoto, Yoko Kiuchi, Chandreyee Ganguli, Kazuyuki Matsubayashi, Yoshiya Uwatoko, Hidenori Takagi We have successfully synthesized a new rhenium-based hexagonal bronze material, Hg$_{x}$ReO$_{3}$, which exhibits superconductivity with the transition temperature $T_c$ = 7.7 K at ambient pressure and 11.1 K at 4 GPa. This compound is a superconductor with the highest $T_c$ among hexagonal bronzes. Moreover, it presents the novel crystallographic feature that $($Hg$_{2})^{2+}$ polycations, in contrast to monatomic cations in known hexagonal bronzes, are incorporated into open channels. There is evidence that conducting electrons tightly couple with Hg-related phonons. Our results inspire detailed studies on the role of the rattling phonon in the occurrence of superconductivity in the hexagonal bronzes. [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