Bulletin of the American Physical Society
APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013; Baltimore, Maryland
Session C13: Focus Session: Topological Materials - Search for New Materials |
Hide Abstracts |
Sponsoring Units: DMP Chair: Seongshik Oh, Rutgers University Room: 315 |
Monday, March 18, 2013 2:30PM - 2:42PM |
C13.00001: Structure and physical properties of Antimony Asenide: a first principle study Dat Do, S. D. Mahanti The group V elements, Sb, As and Bi have attracted renewed attention especially after the discovery of the strong topological insulator Bi$_{1-x}$Sb$_x$. While the mixing of group V elements are thought to be random, recently, Shoemaker et al., arXiv:1210.1986 [cond-mat.mtrl-sci], using single-crystal and high-resolution synchrotron x-ray diffraction, and neutron and x-ray pair distribution function analysis, show that SbAs has chemical ordering. Here we present a detailed theoretical study of the structure and physical properties of SbAs. Our cluster expansion calculation predicts the existence of the chemical ordering, in agreement with experiment. The electronic structure calculations reveal that SbAs is a semimetal with a pseudo gap. We also discuss the similarities and differences of SbAs with its two end-members Sb and As and the Sb-Bi system (bulk), and compare the surface electronic structures of all these systems. [Preview Abstract] |
Monday, March 18, 2013 2:42PM - 2:54PM |
C13.00002: ABSTRACT WITHDRAWN |
Monday, March 18, 2013 2:54PM - 3:06PM |
C13.00003: Driving conventional semiconductors into topological insulating phase Kai Chang Topological insulator (TI) is a central issue of condensed matter physics and has attracted intensive interests recently. TI is a new state of quantum matter possessing insulating bulk and metallic edges. This novel property is caused by a strong spin-orbit interactions (SOIs) in TIs. Usually the topological insulators are narrow band gap systems containing heavy atoms. This requirement limits the members of TIs and its widespread application heavily. Electric fields can drive topological insulator transition in HgTe quantum wells and induces the intrinsic spin Hall effect [1], and can also be used to control surface magnetism of topological insulators [2,3]. More importantly, that conventional semiconductors can be driven into topological insulating phase utilizing the interface polarization induced electric field [4]. We demonstrate theoretically this possibility in GaN/InN/GaN systems. We are moving toward more commonly used semiconductors, such as Silicon.\\[4pt] [1] Phys. Rev. Lett. 100, 056602(2008), W. Yang, Kai Chang, and S. C. Zhang;\newline [2] Phys. Rev. Lett. 106, 097201(2011) J. J. Zhu, D. X. Yao, S. C. Zhang, and Kai Chang\newline [3] Phys. Rev. Lett. 106, 206802(2011); Kai Chang and W. K. Lou\newline [4] Phys. Rev. Lett. (2012), in press; M. S. Miao, Q. Yan, C. G. Van de Walle, W. K. Lou, L. L. Li, and Kai Chang. [Preview Abstract] |
Monday, March 18, 2013 3:06PM - 3:18PM |
C13.00004: Nontrivial spin-texture of the surface states in topological crystalline insulator SnTe Yung Jui Wang, Hsin Lin, Wei-Feng Tsai, Su-Yang Xu, M. Z. Hasan, A. Bansil We present a first principles investigation of the nontrivial surface states and their spin-texture in the topological crystalline insulator SnTe[1,2]. The surface state dispersion on the [001] surface is found to support four Dirac-cones centered along the intersection of the mirror plane and the surface plane. The in-plane spin-texture displays helicity and indicates a nontrivial mirror Chern number of -2, distinct from that of -1 in a Z$_{2}$ topological insulator such as Bi/Sb. The surface state dispersion and the associated spin-texture are shown to provide an experimental route for determining the presence of a nontrivial Chern number. Work supported by the US DOE.\\ \mbox{[1]} T. H. Hsieh \textit{et al.}, Nature Commun. {\bf 3}, 982 (2012).\\ \mbox{[2]} S. Y. Xu \textit{et al.}, Nature Commun. (2012 in press). Preprint at http://arXiv.org/abs/1210.2917. [Preview Abstract] |
Monday, March 18, 2013 3:18PM - 3:30PM |
C13.00005: Flat Chern Band in a Two-Dimensional Organometallic Framework Zheng Liu, Zheng-Fei Wang, Jia-Wei Mei, Yong-Shi Wu, Feng Liu By combining exotic band dispersion with nontrivial band topology, an interesting type of band, namely the flat chern band (FCB), has recently been proposed, in which carriers experience strong Coulomb interaction as well as topological frustration that in together spawn unprecedented topological strongly-correlated electronic states, such as high-temperature fractional quantum hall state. Despite the proposal of several theoretical lattice models, however, it remains a doubt whether such a ``romance of flatland'' could exist in a real material. Here, we present a first-principles design to realize a nearly FCB right around the Fermi level in a two-dimensional (2D) Indium-Phenylene Organometallic Framework (IPOF). Our design in addition provides a general strategy to synthesize topologically nontrivial materials in virtue of organic chemistry and nanotechnology. [Preview Abstract] |
Monday, March 18, 2013 3:30PM - 3:42PM |
C13.00006: Self-assembled structurally complex double-layers of 3-HPLN on Cu(111) Sumit Beniwal, Donna Kunkel, James Hooper, Scott Simpson, Eva Zurek, Axel Enders The self-assembly of 3-Hydroxyphenalenone (3-HPLN) on metal surface has been studied with scanning tunneling microscopy and first principles theory. 3-HPLN belongs to the group of topological ferroelectric organics, where the electric polarization is related to the hydrogen bonds between the molecules. It is observed that the structure of the self-assembled 2D networks is strongly dependent of the substrate material and the preparation conditions. Of particular interest in this presentation is the chiral Kagome lattices of 3-HPLN observed after annealing on Cu(111). A unique feature of the molecular network is the CH-pi bond formation between flat-lying molecules and molecules attached perpendicular to the surface. It will be demonstrated that the addition of a second layer on the first monolayer of 3-HPLN triggers a structural reorganization in the first layer, to form a complex double layer structure that is not merely the addition of two single layers. The chiral pores in the film can serve as a host or a template for metal nanoparticles, such as Fe. The so-obtained hybrid nanostructures might be a useful milestone towards self-asembled metal-organics multiferroics. [Preview Abstract] |
Monday, March 18, 2013 3:42PM - 4:18PM |
C13.00007: Topological Insulators: A New Platform for Fundamental Science and Applications Invited Speaker: Arun Bansil Topological insulators constitute a new phase of quantum matter whose recent discovery has focused world-wide attention on wide-ranging phenomena in materials driven by spin-orbit coupling effects well beyond their traditional role in determining magnetic properties. I will discuss how by exploiting electronic structure techniques we have been able to predict and understand the characteristics of many new classes of binary, ternary and quaternary topologically interesting systems. [1-4] The flexibility of chemical, structural and magnetic parameters so obtained is the key ingredient for exploring fundamental science questions, including novel spin-textures and exotic superconducting states, as well as for the realization of multi-functional topological devices for thermoelectric, spintronics, information processing and other applications. [5-7] I will also highlight new insights that have been enabled through our material-specific modeling of angle-resolved photoemission (ARPES) and scanning tunneling (STS) spectroscopies of topological surface states, including effects of the photoemission and tunneling matrix element, which is well-known to be important for a robust interpretation of various highly resolved spectroscopies. [8,9] Work supported by the Materials Science \& Engineering Division, Basic Energy Sciences, U. S. D. O. E.\\[4pt] [1] H. Lin \textit{et al.}, \textit{Nature Materials} 9, 546 (2010).\\[0pt] [2] H. Lin \textit{et al.}, \textit{Physical Review Letters} 105, 036404 (2010). \\[0pt] [3] T. H. Hsieh \textit{et al.}, \textit{Nature Communications} 3, 982 (2012). \\[0pt] [4] S. Y. Xu \textit{et al.}, \textit{Nature Communications} 3, 1192 (2012).\\[0pt] [5] S. Basak \textit{et al.}, \textit{Physical Review B-Rapid} 84, 121401 (2011).\\[0pt] [6] S-Y Xu \textit{et al.}, \textit{Nature Physics} 8, 616 (2012).\\[0pt] [7] S. Y. Xu \textit{et al.}, \textit{Science} 332, 560 (2011).\\[0pt] [8] Y. Okada \textit{et al.}, \textit{Physical Review Letters} 106, 206805 (2011).\\[0pt] [9] Y. Sakurai \textit{et al.}, \textit{Science} 332, 698 (2011). [Preview Abstract] |
Monday, March 18, 2013 4:18PM - 4:30PM |
C13.00008: Metal-Insulator Transition in Epitaxial Pyrochlore Iridates Bi$_2$Ir$_2$O$_7$ thin Films Jiun-Haw Chu, Jian Liu, Di Yi, C. Rayan-Serrao, S. Suresha, Xavi Marti, Scott Riggs, Max Shapiro, Fisher Ian, R. Ramesh Recently there is a surge of interest in searching for topological order in correlated electronic systems such as transition metal oxides. The strong spin-orbit interaction of 5d electrons and the geometric frustration in the crystal lattice make the pyrochlore iridate(A$_2$Ir$_2$O$_7$) an ideal candidate to achieve this goal. Pioneering experiments on bulk polycrystalline and single crystal samples revealed a temperature dependent metal-insulator transition coupled to a long range magnetic order, and the transition temperature can be tuned by either A-site ionic radius or an external pressure. In this talk we present our efforts to understand and control the metal-insulator transition and the underlying electronic structure of pyrochlore iridates via epitaxial Bi$_2$Ir$_2$O$_7$ thin films. Bulk Bi$_2$Ir$_2$O$_7$ is located at the metallic side of the phase diagram. However as the film's thickness decreases the transport evolves from a metallic to a strongly localized character. Resonant X-ray spectroscopy suggests that the density of states near Fermi level is dominated by the Ir J$_eff$=1/2 states. Intriguingly, the magnetoresistance shows a linear field dependence over a wide range of fields at low temperatures, which is possibly consistent with the existence of Dirac nodes. [Preview Abstract] |
Monday, March 18, 2013 4:30PM - 4:42PM |
C13.00009: Na$_2$IrO$_3$ as a Novel Relativistic Mott Insulator with a 340\,meV Gap Riccardo Comin, G. Levy, I. Elfimov, A. Damascelli, D. Stricker, J. Hancock, D. van der Marel, Y. Singh, P. Gegenwart We have studied Na$_{2}$IrO$_{3}$ by ARPES, optics, and band structure calculations in the local-density approximation (LDA). The weak dispersion of the Ir 5$d$-$t_{2g}$ manifold highlights the importance of structural distortions and spin-orbit coupling (SO) in driving the system closer to a Mott transition. We detected an insulating gap $\Delta_{gap}\!\simeq\!340$\,meV which, at variance with a Slater-type description, is already open at 300\,K and does not show significant temperature dependence even across $T_N\!\simeq\!15$\,K. An LDA analysis with the inclusion of SO and Coulomb repulsion U revealed that, while the prodromes of an underlying insulating state are already found in LDA+SO, the correct gap magnitude can only be reproduced by LDA+SO+U, with $U\!=\!3$\,eV. This establishes Na$_2$IrO$_3$ as a novel type of Mott-like correlated insulator in which Coulomb and relativistic effects have to be treated on an equal footing. [Preview Abstract] |
Monday, March 18, 2013 4:42PM - 4:54PM |
C13.00010: Single surface state at a strongly correlated electronic structure in Na$_{2}$IrO$_{3}$: a candidate d-electron topological insulator Qiang Wang, Yue Cao, Justin Waugh, Tongfei Qi, Oleksandr Korneta, Gang Cao, Daniel Dessau We have performed angle-resolved photoemission spectroscopy (ARPES) on Na$_{2}$IrO$_{3}$, a 5d transition metal oxide (TMO) which is a strong insulator with a honeycomb lattice structure and has been theoretically proposed as a candidate for a new class of topological insulators (TIs). The near E$_{F}$ electronic structure of Na$_{2}$IrO$_{3}$ was carefully mapped, which shows an overall agreement to the first-principle calculations with spin-orbit (SO) coupling and electron correlation (U), though certain discrepancy remains. Specifically, we found an extra electron-like pocket near the Fermi level with Dirac-cone-like dispersion around $\Gamma $ point. The further photon energy dependent studies show no k$_{z}$-dispersion of this electron-like pocket, and the metal deposition studies show a great enhancement and sharpening of this feature. These results confirm its surface state nature and suggest a possible single topological surface state at the Brillouin zone (BZ) center in Na$_{2}$IrO$_{3}$. [Preview Abstract] |
Monday, March 18, 2013 4:54PM - 5:06PM |
C13.00011: Multiple Topological phase transitions induced by magnetic ordering in Cd$_2$Ru$_2$O$_7$ Hongming Weng, Quansheng Wu, Zhong Fang, Xi Dai The magnetic and electronic structures of pyrochlore Ruthenates Cd$_2$Ru$_2$O$_7$ are studied by means of first principle calculation. We find that the paramagnetic phase stabilized in high temperature is a three dimensional $Z_2$ topological insulator. While in low temperature the all-in/all-out type anti-ferromagnetic order appears, which leads to three different topologically non-trivial phase can be stabilized upon cooling, namely the axion insulator, Weyl semi-metal and intrinsic polarization phases. The detailed evolution of both bulk and surface electronic structures as the function of magnetic order parameter are obtained. Based on the above observations we propose several experimental consequences, which can be detected by further experiments. [Preview Abstract] |
Monday, March 18, 2013 5:06PM - 5:18PM |
C13.00012: Topological phases in layered pyrochlore oxide thin films along the [111] direction Xiang Hu, Andreas R\"uegg, Gregory A. Fiete We theoretically study a multi-band Hubbard model of pyrochlore oxides of the form A$_2$B$_2$O$_7$, where B is a heavy transition metal ion with strong spin-orbit coupling, in a thin film geometry orientated along the [111] direction. Along this direction, the pyrochlore lattice consists of alternating kagome and triangular lattice planes of B ions. We consider a single kagome layer, a bilayer, and the two different trilayers. As a function of the strength of the spin-orbit coupling, the direct and indirect $d$-orbital hopping, and the band filling, we identify a number of scenarios where a non-interacting time-reversal invariant Z$_2$ topological phase is expected and we suggest some candidate materials. We study the interactions in the half-filled $d$-shell within Hatree-Fock theory and identify parameter regimes where a zero magnetic field Chern insulator with Chern number $\pm1$ can be found. The most promising geometries for topological phases appear to be the bilayer which supports both a Z$_2$ topological insulator and a Chern insulator, and the triangular-kagome-triangular trilayer which supports a relatively robust Chern insulator phase. [Preview Abstract] |
Monday, March 18, 2013 5:18PM - 5:30PM |
C13.00013: Samarium Hexaboride - First True 3D Topological Insulator Steven Wolgast, \c{C}a\u{g}liyan Kurdak, Kai Sun, James Allen, Zachary Fisk Although many important breakthroughs in the study of topological states of matter have been achieved within the last few years, a very important link still remains missing--the experimental discovery of a true 3D topological insulator. Materials currently known to have topological surface states (e.g. Bi$_{1-x}$Sb$_{x}$, Bi$_{2}$Se$_{3}$ and Bi$_{2}$Te$_{3}$) are also bulk conductors, and thus do not have a well-defined topological index. Recent calculations of the heavy-fermion Kondo insulator Samarium Hexaboride (SmB$_{6}$) have predicted the possibility of in-gap topological surface states in this material. Meanwhile, the conjectured existence of a topologically-protected surface state in SmB$_{6}$ could resolve many of the long-standing puzzles surrounding its low-temperature transport properties. Here we study the transport properties of SmB$_{6}$ with a novel configuration designed to distinguish bulk-dominated conduction from surface-dominated conduction. We find that SmB$_{6}$ is a true topological insulator with an insulating bulk and a metallic surface. This discovery resolves the standing puzzles about the strange transport behavior of this material, and it provides the first material in which transport properties of a 3D topological state can be studied. [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