Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session B3: Topological insulators: General Theory 
Hide Abstracts 
Sponsoring Units: DCMP Chair: Hua Chen, University of Texas, Austin Room: 262 
Monday, March 13, 2017 11:15AM  11:27AM 
B3.00001: Anisotropic magnetoresistance of topologicalinsulator surface states in a parallel magnetic field A. H. MacDonald, C. M. Canali, C. M. Holmqvist, A. Pertsova The influence of external perturbations on the surfacestate (SS) transport properties of topological insulators (TI) is presently the subject of intense investigation. We report on a theoretical analysis of the influence of an inplane magnetic field on SS properties. For 2D electron systems confined to semiconductor quantum wells, inplane magnetic fields yield transport anisotropy that can be traced to an enhancement in quasiparticle mass for motion in the inplane direction perpendicular to the field. To verify the existence of a similar anisotropy in the TI SS system, we consider a longwavelength fourband model of SSs that is relevant for several TIs with the Bi$_{\mathrm{2}}$Se$_{\mathrm{3}}$ crystal structure. An inplane field influences the orbital motion, but leaves the SS momenta as good quantum numbers. The ensuing set of four coupled Dirac's equations, is solved numerically. We find that the magnetic field introduces an inplane anisotropy in the energy dispersion of Dirac's states which affects the conductivity. We compare the size of the anisotropic orbital magnetoresistance with the anisotropy originating from Zeeman coupling. The results of this approximate continuum model are compared with the predictions of a realistic tightbinding model for Bi$_{\mathrm{2}}$Se$_{\mathrm{3}}$ thin films. [Preview Abstract] 
Monday, March 13, 2017 11:27AM  11:39AM 
B3.00002: Bulk excitons in topological insulators Andrew Allocca, Dmitry Efimkin, Victor Galitski Excitons formed from surface states of topological insulators have been thoroughly studied in recent years, but little attention has been given to the properties of excitons formed in the bulk of these materials. In this work we examine the properties of these bulk excitons, focusing specifically on the signatures of nontrivial topology in the excitonic. We consider models which can be easily tuned to be either topologically trivial or nontrivial, allowing us to see how the excitonic spectrum and wave functions change between the two regimes. [Preview Abstract] 
Monday, March 13, 2017 11:39AM  11:51AM 
B3.00003: Theory of hysteretic magnetotransport on the surface of a magnetic threedimensional topological insulator Kunal Tiwari, William Coish, Tami PeregBarnea We study the magnetoconductance of the surface of a magnetic strong threedimensional topological insulator (MTI)\footnote{CuiZu Chang {\it et al}. Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator. {\it Science} \textbf{340}, 167170 (2013)}{$^{,}$}\footnote{W. Wang {\it et al}. Visualizing ferromagnetic domain behavior of magnetic topological insulator thin films. {\it NPJ Quantum Materials} \textbf{1}, 16023 (2016)}. An MTI surface is characterized by a twodimensional Dirac cone dispersion which is gapped by the local magnetization. While the magnetization causes a gap, magnetic domain walls support onedimensional chiral states within the bulk and surface gaps. These domainwall states carry current and therefore influence the systemâ€™s magnetoconductance. Our model reproduces a hysteretic feature in magnetoconductance which is seen in experiment\footnote{Y. Nakajima {\it et al}. Onedimensional edge state transport in a topological Kondo insulator. {\it Nature Physics} \textbf{12}, 213217 (2016)}. [Preview Abstract] 
(Author Not Attending)

B3.00004: Signatures of topological phase transition in 3d topological insulators from dynamical axion response Imam Makhfudz Axion electrodynamics, first proposed in the context of particle physics, manifests itself in condensed matter physics in the topological field theory description of 3d topological insulators and gives rise to magnetoelectric effect, where applying magnetic (electric) field $\mathbf{B}(\mathbf{E})$ induces polarization (magnetization) $\mathbf{p}(\mathbf{m})$. We use linear response theory to study the associated topological current using the FuKaneMele model of 3d topological insulators in the presence of timedependent uniform weak magnetic field. By computing the dynamical current susceptibility $\chi^{\mathbf{j}_p\mathbf{j}_p}_{ij}(\omega)$, we discover from its static limit an `order parameter' of the topological phase transition between weak topological (or ordinary) insulator and strong topological insulator, found to be continuous.The $\chi^{\mathbf{j}_p\mathbf{j}_p}_{ij}(\omega)$ shows a signchanging singularity at a critical frequency with suppressed strength in the topological insulating state. Our results can be verified in current noise experiment on 3d TI candidate materials for the detection of such topological phase transition. [Preview Abstract] 
Monday, March 13, 2017 12:03PM  12:15PM 
B3.00005: Degeneracy and topology for the magnetic space group of CuBi$_2$O$_4$ Andreas Schnyder, YangHao Chan, ChingKai Chiu In the presence of antiferromagnetic order CuBi$_2$O$_4$ belongs to one of $\#56$ magnetic space groups. Inversiontimereversal symmetry leads to 2fold degeneracy of all the energy bands in the entire Brillouin zones. It surprises us that nonsymmorphic symmetries in the subgroup $\#56$ space group protect 4fold degeneracy in a symmetric line. We further investigate the topology and surface states of CuBi$_2$O$_4$ stemming from its magnetic space group. [Preview Abstract] 
Monday, March 13, 2017 12:15PM  12:27PM 
B3.00006: Nematic Order on the Surface of a Threedimensional Topological Insulator Hennadii Yerzhakov, Rex Lundgren, Joseph Maciejko We develop a field theoretic description of nematic order and investigate its consequences on the surface of a threedimensional topological insulator with a single Dirac cone in both the nodal (the Fermi energy is at the Dirac point) and doped limit. In the nodal limit at zero temperature, we find a first order phase transition to a nematic phase at the meanfield level. Upon increasing the temperature, we find a tricritical point and a continuous critical phase boundary. In the doped limit, we find a continuous phase transition to a nematic helical Fermi liquid. One of the unique features of this nematic helical Fermi liquid phase which, in principle, can be observed via spinresolved angleresolved photoemission spectroscopy, is the breakdown of spinmomentum locking, except for certain highlysymmetric momenta. Finally, we discuss the nonFermi liquid behavior at and near the isotropictonematic phase transition. [Preview Abstract] 
Monday, March 13, 2017 12:27PM  12:39PM 
B3.00007: Firstorder quantum phase transition in threedimensional topological band insulators Vladimir Juricic, David Abergel, Alexander Balatsky It is commonly assumed that the transition between topologically distinct noninteracting gapped phases of fermions is necessarily accompanied by the closing of the gap as long as the symmetries of the Hamiltonian are maintained. We show that such a quantum phase transition is possible without closing the gap in the case of a threedimensional topological band insulator [1]. We demonstrate this by calculating the free energy of the BernevigHughesZhang model, and show that as the band curvature continuously varies, a jump between the band gap minima corresponding to the topologically trivial and nontrivial insulators occurs. Therefore, this first order phase transition is a generic feature of threedimensional topological bandinsulators. For a certain parameter range we predict a reentrant topological phase transition. We discuss our findings in connection with the recent experimental observation of a discontinuous phase transition in a family of topological crystalline insulators. [1] V. Juricic, D. S. L. Abergel, and A. V. Balatsky, arXiv: 1608.07819. [Preview Abstract] 
Monday, March 13, 2017 12:39PM  12:51PM 
B3.00008: Electromagnetic Response of Threedimensional Topological Crystalline Insulators Srinidhi Ramamurthy, Yuxuan Wang, Taylor Hughes Topological crystalline insulators (TCI) are a new class of materials which have metallic surface states on select surfaces due to point group crystalline symmetries. In this letter, we consider a model for a threedimensional (3D) topological crystalline insulator with Dirac nodes occurring on a surface that are protected by the mirror and time reversal symmetry. We demonstrate that the electromagnetic response for such a system is characterized by a $1$form $b_{\mu}$. $b_{\mu}$ can be inferred from the locations of the surface Dirac nodes in energymomentum space. From both the effective action and analytical band structure calculations, we show that the vortex core of $\vec b$ or a domain wall of a component of $\vec b$ can trap surface charges. [Preview Abstract] 
Monday, March 13, 2017 12:51PM  1:03PM 
B3.00009: Emergence of topological quantum effects in thin film topological insulators through defect engineering Maryam Salehi, Nikesh Koirala, Matthew J. Brahlek, Jisoo Moon, Seongshik Oh Topological insulators (TIs) have received intense attention over the past several years with the hope of new age of topological electronics or topotronics. However, defects, particularly interfacial defects, have been a major bottleneck along the way. In this talk, I will discuss how defects have been affecting the properties of thin film TIs and show how defectengineered TI thin films can reveal heretofore unobservable aspects of TIs such as topological surfacestate quantum Hall effect, (quantum) anomalous Hall effect, quantized Faraday and Kerr rotation, and finitesize topological phase transition, etc. [Preview Abstract] 
Monday, March 13, 2017 1:03PM  1:15PM 
B3.00010: Interfacialstate coupling induced topological phase transitions in materials with multiple valleys Xiao Li, Qian Niu A defining feature of topological insulating phases is symmetryprotected interfacial Dirac states. By exploiting couplings of multiple interfacial Dirac valleys in a binary superlattice, we establish that contrasting valley parity exchange forges a unifying bridge to create various topological phases. Ab initio simulations demonstrate that topological phase transitions can occur due to valleydependent interfacialstate coupling in both twodimensional and threedimensional IVVI topological crystalline insulators with multiple valleys. [Preview Abstract] 
Monday, March 13, 2017 1:15PM  1:27PM 
B3.00011: Ferromagnetic transition and fluctuationinduced DzyaloshinskiiMoriya interaction at the surface of threedimensional topological insulators Flavio S. Nogueira, Ferhat Katmis, Jagadeesh Moodera, Ilya Eremin A ferromagnetic insulator (FMI) proximate to the surface of a threedimensional topological insulator (TI) generate a gap in the spectrum of surface Dirac fermions, provided an outofplane exchange exists. We study the ferromagnetic transition in TIFMI structures and show that fluctuations from Dirac fermions induce a DzyaloshinskiiMoriya (DM) interaction in the effective free energy of the FMI. This DM interaction arises only if the chemical potential is nonzero. Thus, if the proximity effect gaps the Dirac fermions, this means that the Fermi level must be outside the gap in order for a DM term to be induced. We also show that the Curie temperature of the ferromagnetic state at the interface between the TI and FMI is necessarily higher than the bulk Curie temperature of the FMI. This result is corroborated by recent experiments in Bi$_2$Se$_3$EuS bilayer structures. These results imply an interface critical behavior very different from the bulk FMI. [Preview Abstract] 
Monday, March 13, 2017 1:27PM  1:39PM 
B3.00012: Robust spinpolarized midgap states at step edges of topological crystalline insulators. Domenico Di Sante, Paolo Sessi, Martin Greiter, Titus Neupert, Giorgio Sangiovanni, Tomasz Story, Ronny Thomale, Matthias Bode Topological crystalline insulators are materials in which the crystalline symmetry leads to topologically protected surface states with a chiral spin texture, rendering them potential candidates for spintronics applications. In this talk, I report on the discovery of onedimensional midgap states at oddatomic surface step edges of the three dimensional topological crystalline insulator (Pb,Sn)Se. A minimal toy model and realistic tightbinding calculations identify them as spinpolarized flat bands connecting two Dirac points. The midgap states inherit stability through the twodimensional Dirac metal from the threedimensional bulk insulator. This makes (Pb,Sn)Se the first example for a crystal symmetryprotected hierarchy of one and two dimensional topological modes, which we experimentally prove to result in a striking robustness to defects, strong magnetic fields, and elevated temperature. [Preview Abstract] 
Monday, March 13, 2017 1:39PM  1:51PM 
B3.00013: Optical properties of topological insulator nanoparticles Gleb Siroki, Derek Lee, Peter Haynes, Vincenzo Giannini Topological insulators are materials that have metallic surface states protected by timereversal symmetry. Such states are delocalised over the surface and are immune to nonmagnetic defects and impurities. Building on previous work [1] we have studied the interaction of light with topological insulator nanoparticles. Our main finding is that the occupied surface states can lead to charge density oscillations akin to plasmons in metallic nanoparticles. Furthermore, these oscillations can couple to phonons forming a previously unreported excitation [2]. Because the states are localised at the surface a small number of them is enough to change the absorption spectrum of a particle containing many thousands of atoms. We are going to show how the effect can be adjusted by varying the particle's size and shape. Furthermore, we will discuss the robustness of the effect in the presence of disorder. In conclusion, topological nanoparticles can be used as a highlytunable building block to create a metamaterial operating in THz range. This may be interesting for plasmonics and metamaterials communities as well as researchers working on cavity electrodynamics and quantum information. \newline [1] Imura et al, PRB 86, 235119 (2012)\newline [2] Siroki et al, Nat. Comm. 7, 12375 (2016) [Preview Abstract] 
Monday, March 13, 2017 1:51PM  2:03PM 
B3.00014: Effect of disordered geometry on transport properties of three dimensional topological insulator nanowires Emmanouil Xypakis, Jun Won Rhim, Roni Ilan, Jens H. Bardarson Three dimensional topological insulator nanowires are materials which, while insulating in the bulk, have a metallic boundary described by a two dimensional Dirac Hamiltonian with antiperiodic boundary conditions. Transport properties of this system have been extensively studied in the limit where the surface manifold is conformally flat (e.g., a cylinder) in the presence of a random disordered scalar potential. In this talk I will discuss how this picture is altered when a more realistic surface manifold is chosen, such as a cylinder with a randomly fluctuating radius. [Preview Abstract] 
Monday, March 13, 2017 2:03PM  2:15PM 
B3.00015: Effects of electronic interactions near the topological semimetalinsulator quantum phase transition in two dimensions Bitan Roy, Matthew Foster The quasiparticle dispersion of gapless excitations residing at the quantum critical point (QCP) separating a two dimensional topological Dirac semimetal and a symmetry preserving band insulator, displays distinct powerlaw dependence with various components of spatial momenta. In this talk first I will review scaling of various thermodynamic and transport quantities at this QCP. Next I will demonstrate that even though such noninteracting QCP is stable against sufficiently weak but generic shortrange interaction, the direct transition between the Dirac semimetal and band insulator can either (i) become a fluctuation driven first order transition, or (ii) get eliminated by an intervening broken symmetry phase, with staggered pattern in charge or spin being two prominent candidates, for sufficiently strong interactions. The novel quantum critical phenomena associated with the instability of critical excitations toward the formation of various broken symmetry phases will be discussed. Relevance of our study in strained graphene, black phosphorus, pressured organic compounds and oxide heterostructure will be highlighted. [Preview Abstract] 
Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit membership organization working to advance the knowledge of physics. 
© 2020 American Physical Society
 All rights reserved  Terms of Use
 Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 207403844
(301) 2093200
Editorial Office
1 Research Road, Ridge, NY 119612701
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700