Bulletin of the American Physical Society
APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013; Baltimore, Maryland
Session W1: Invited Session: Superconductivity at High Pressure |
Hide Abstracts |
Sponsoring Units: DCMP DMP Chair: Viktor Struzhkin, Carnegie Institution for Science Room: Ballroom I |
Thursday, March 21, 2013 2:30PM - 3:06PM |
W1.00001: Achieving higher \textit{T}$_{\mathrm{C}}$ superconductivity in dense cuprates, iron selenides, and hydrocarbons Invited Speaker: Xiao-Jia Chen Pressure plays an essential role in inducing or tuning superconductivity as well as shedding insight on the mechanism of superconductivity. There are much rich phase diagrams in unconventional superconductors under pressure. Finding ways to control the quantum coherence properties to have a higher critical temperature $T_{\mathrm{C}}$ than the material has remains a challenge. Here we will talk about our recent experimental efforts in achieving higher temperature superconductivity in cuprates, iron selenides, and hydrocarbons. We will show how to enhance remarkably $T_{\mathrm{C}}$ through the pressure tuning of competing electronic order in multilayer cuprates [1] and how to have superconductivity in two distinct regimes in iron selenides [2,3]. We will present a discovery of an enhancement of $T_{\mathrm{C}}$ at more than doubled ambient value in a highly compressed aromatic hydrocarbon [4]. Our results have important implications for designing and engineering superconductors with much higher $T_{\mathrm{C}}$s at ambient conditions.\\[4pt] [1] X. J. Chen, V. V. Struzhkin, Y. Yu, A. F. Goncharov, C. T. Lin, H. K. Mao, and R. J. Hemley, \textit{Nature} \textbf{466}, 950-953 (2010).\\[0pt] [2] L. L. Sun, X. J. Chen, J. Guo, P. W. Gao, H. D. Wang, M. H. Fang, X. L. Chen, G. F. Chen, Q. Wu, C. Zhang, D. C. Gu, X. L. Dong, K. Yang, A. G. Li, X. Dai, H. K. Mao, and Z. X. Zhao, \textit{Nature} \textbf{483}, 67-69 (2012) .\\[0pt] [3] X. J. Chen, Q. Huang, S. B. Wang, J. X. Zhu, W. Bao, M. H. Fang, J. B. Zhang, L. Y. Tang, Y. M. Xiao, P. Chaw, J. Shu, W. L. Mao, V. V. Struzhkin, R. J. Hemley, and H. K. Mao, unpublished.\\[0pt] [4] X. J. Chen, X. F. Wang, Z. X. Qin, H. Wu, Q. Z. Huang, T. Muramatsu, J. J. Ying, P. Cheng, Z. J. Xiang, X. H. Chen, W. G. Yang, V. V. Struzhkin, and H. K. Mao, unpublished. [Preview Abstract] |
Thursday, March 21, 2013 3:06PM - 3:42PM |
W1.00002: Elemental superconductivity at high pressure Invited Speaker: Katsuya Shimizu Most of superconducting materials show a negative pressure effect in the superconducting critical temperature, $T_{c}$, however, some of simple elements show the positive effect. It has been already revealed that not a few elements that are not the superconductor at ambient pressure became superconductive under combination of low temperature and high pressure. Not only for searching higher $T_{c}$ but also for understanding the fundamental mechanism of ``superconductivity'' systematically, we have worked on pressure effect as well as pressure-induced superconductivity especially in simple elements. Here we report two characteristic results of the high-pressure phenomena including superconductivity in calcium (Ca) and lithium (Li). The $T_{c}$ of Ca increases with pressure and reaches 29 K, the highest $T_{c}$ in elements, at very high pressure above 200 GPa. The lightest metal element of Li exhibits relatively high $T_{c}$ at high pressure, however suddenly becomes semiconductor at 80 GPa. Recently we discovered the reentrance of the superconductivity in Li at around 120 GPa. [Preview Abstract] |
Thursday, March 21, 2013 3:42PM - 4:18PM |
W1.00003: NMR Studies of Novel Electronic Phases in Low Dimensional Molecular Solids at High Pressure and Low Temperature Invited Speaker: Stuart Brown Molecular superconductors are known for anisotropic electronic band structure, correlations, and a sensitivity to mechanical or chemical pressure which acts to control the relative strength of the respective kinetic and potential energies. Modest pressures, of order 1 GPa are commonly used to continuously tune from a Mott insulating ground state to a superconducting state, and NMR has been particularly successful in identifying the orders involved, and the nature of the excitations in the various phases encountered. The family of quasi-two dimensional systems $\kappa$-(BEDT-TTF)$_2$X ({\it e.g.}, X=Cu(NCS)$_2$, Cu[N(CN)$_2$]Cl) includes a line of first order phase transitions separating the Mott and superconducting phases, with the superconducting state exhibiting signatures for line nodes associated with an order parameter sign-change over the Fermi surface. The pressure/temperature phase diagram of the quasi-one dimensional materials (TMTSF)$_2$X, X=PF$_6$, ClO$_4$,...) includes more phases, as a consequence of effective 1/4-filling and a substantial density wave susceptibility. The SC ground state is singlet, and there is evidence for a sign-change of the order parameter over the Fermi surface. The high-conductivity normal state exhibits properties associated with two-dimensional spin fluctuations, with signatures in the relaxation rate, as well as transport that are reminiscent of behaviors observed in other correlated superconductors. [Preview Abstract] |
Thursday, March 21, 2013 4:18PM - 4:54PM |
W1.00004: Pressure effects in cuprate and iron-based superconductors studied by muon spin rotation Invited Speaker: Hugo Keller Pressure effect (PE) studies of physical parameters of solid state systems allow one to investigate the properties of a material as a function of tuned inter-atomic distances. Such studies are performed on the same material with well defined composition and microstructure which is often advantageous, since {\em e.g.} chemical tuning of material properties (chemical pressure) may give rise to a number of misleading experimental artefacts. Muon-spin rotation ($\mu$SR) is a powerful and highly sensitive tool for probing static and dynamic magnetic fields in solids on the atomic scale. In type-II superconductors the nanoscale variation of the local magnetic field in the vortex state can be detected by $\mu$SR from which the magnetic penetration depth (superfliud density) can be extracted. Furthermore, $\mu$SR is a unique microscopic technique to explore magnetic ordering phenomena and various magnetic phases in solids. At the Paul Scherrer Institute (PSI) a high-pressure set-up was realized which allows to perform $\mu$SR experiments at hydrostatic pressures up to 25 kbar and low temperatures ($\simeq 0.3$~K) [1]. Such experiments open a wide spectrum of new possibilities for investigating the superconducting and magnetic properties of novel materials, such as high-temperature superconductors and related magnetic materials. Here, we present some representative examples of such $\mu$SR pressure studies carried out at PSI: Iron-based superconductors turned out to exhibit a rich and complex phase diagram which strongly depends on pressure [2,3]. $\mu$SR pressure experiments have significantly contributed to a better understanding of these novel class of superconductors [1,2]. In a further $\mu$SR study the PE on the magnetic penetration depth in cuprate superconductors was investigated and found to exhibit an interesting relation to the observed isotope effect [4]. Very recently, we also investigated the PE on the magnetic penetration depth in the heavy fermion system CeCoIn$_{5}$, revealing a strong increase of the superfluid density with pressure [5].\\[4pt] [1] A. Maisuradze {\it et al.}, arXiv:1211.3584 (2012); M. Bendele {\it et al.}, Phys. Rev. B {\bf 85}, 064517 (2012). \\[0pt] [2] R. Khasanov {\it et al.}, Phys. Rev. Lett. {\bf 104}, 087004 (2010). \\[0pt] [3] M. Bendele {\it et al.}, Phys. Rev. Lett. {\bf 104}, 087003 (2010). \\[0pt] [4] A. Maisuradze {\it et al.}, Phys. Rev. B {\bf 84}, 184523 (2011). \\[0pt] [5] L. Howald {\it et al.}, submitted for publication. [Preview Abstract] |
Thursday, March 21, 2013 4:54PM - 5:30PM |
W1.00005: Pressure tuning of magnetic fluctuation and superconductivity in CeCoIn$_5$ Invited Speaker: Carmen Almasan One of the greatest challenges to Landau's Fermi liquid theory -- the standard theory of metals - is presented by complex materials with strong electronic correlations. The non-Fermi liquid transport and thermodynamic properties of these materials are often explained by the presence of strong quantum critical fluctuations associated with a quantum phase transition that happens at a quantum critical point (QCP). The heavy-fermion material CeCoIn$_{5}$ is a prototypical system for which its pronounced non-Fermi liquid behavior in the normal state and unconventional superconductivity are thought to arise from the proximity of this system to a QCP [1-5]. Previous experiments address the physics of this QCP by extrapolating results obtained in the normal state, i.e., there were no \textit{direct} probes of antiferromagnetism and quantum criticality in the superconducting state. This motivated us to study the transport in the mixed state, thus revealing the physics of antiferromagnetism and quantum criticality of the underlying normal state [6]. In this talk I will present the results obtained in these studies by measuring the vortex core dissipation under applied hydrostatic pressure ($P$). The vortex core resistivity increases sharply with decreasing magnetic field ($H)$ and temperature ($T)$ due to quasiparticle scattering on critical antiferromagnetic fluctuations. This behavior is greatly suppressed with increasing $P$. Using our experimental results, we obtained an explicit equation for the antiferromagnetic boundary inside the superconducting dome and constructed an $H-T-P$ phase diagram. This work provides direct evidence for a quantum critical line inside the superconducting phase and reveals the close relationship between quantum criticality, antiferromagnetism, and superconductivity.\\[4pt] In collaboration with T. Hu, H. Xiao, T. A. Sayles, M. Dzero, and M. B. Maple.\\[4pt] [1] V. A. Sidorov et al., Phys. Rev. Lett. 89, 157004 (2002). \newline [2] J. Paglione et al., Phys. Rev. Lett. 91, 246405 (2003). \newline [3] S. Singh et al., Phys. Rev. Lett. 98, 057001 (2007). \newline [4] S. Zaum et al., Phys. Rev. Lett. 106, 087003 (2011). \newline [5] F. Ronning et al., Phys. Rev. B 73, 064519 (2006). \newline [6] T. Hu et al., Phys. Rev. Lett. 108, 056401 (2012). [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