Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session R44: Heavy Fermion Systems as a Platform for Strongly Correlated Electronic TopologyInvited
|
Hide Abstracts |
Sponsoring Units: DCMP Chair: Piers Coleman, Rutgers University Room: BCEC 210C |
Thursday, March 7, 2019 8:00AM - 8:36AM |
R44.00001: Weyl-Kondo semimetals: Symmetries, signatures and nearby quantum phases Invited Speaker: Sarah Grefe In the last few years, manifestations of the long-anticipated Weyl semimetal have been observed in weakly correlated materials. In the context of a global phase diagram for strongly correlated systems with a large spin-orbit coupling, the prototypical heavy fermion systems have emerged as an important platform for topological metals. We have recently advanced a strongly correlated topological phase, the Weyl-Kondo semimetal (WKSM) [1], which exhibits Kondo effect-driven nodal quasiparticles. The Weyl nodes are pinned near the Fermi energy by strong correlations along with space group symmetry. One signature of this WKSM phase is a specific heat varying as T3 below the Kondo temperature, with a colossal prefactor, as observed in the noncentrosymmetric heavy fermion semimetal Ce3Bi4Pd3 [2]. Experiments on Ce3Bi4Pd3 have also demonstrated a nonlinear spontaneous Hall response and an even-in-field Hall resistivity, which are attributed to the large Berry curvature dipole of a WKSM with tilted nodes [3]. Both illustrate that signatures of topological phases driven by strong correlations are often distinct from those typical for weakly correlated systems. Finally, in related models we have found how the WKSM connects with proximate topologically distinct phases, such as a Kondo Insulator and a Dirac-Kondo semimetal, as well as magnetic states. I will present these results, and discuss their place in the heavy fermion global phase diagram that the topological paradigm has enriched. |
Thursday, March 7, 2019 8:36AM - 9:12AM |
R44.00002: Kondo-Weyl semimetal behavior in Ce3Bi4Pd3 Invited Speaker: Sami Dzsaber In heavy fermion systems the Kondo effect stabilizes strongly renormalized heavy electronic bands, and promotes novel quantum phases and excitations. Recently, the discovery of topologically non-trivial insulators, as well as Dirac and Weyl semimetals with 3D bulk linear electronic dispersion has triggered a lot of interest. So far, investigations have focused on non-interacting settings, but it is of great interest to also explore the interplay of strong correlations and topology. For this purpose we have searched for topologically non-trivial phases in heavy fermion systems. Indeed, by tuning the spin-orbit coupling strength by Pt-Pd substitution in Ce3Bi4(Pt,Pd)3, we have discovered a transformation from a Kondo insulator in Ce3Bi4Pt3 to a semimetal in Ce3Bi4Pd3 [1]. The latter shows the thermodynamic hallmark of strongly renormalized linear electronic bands [1], as recently predicted for a Weyl-Kondo semimetal [2]. Strikingly, as full Kondo coherence sets in, a large spontaneous Hall effect appears. As the material is entirely nonmagnetic, this is direct evidence of a huge Berry curvature dipole in the absence of time-reversal symmetry breaking. We attribute this effect to the topological nature of this noncentrosymmetric material, in the form of tilted Kondo-driven Weyl nodes [3]. |
Thursday, March 7, 2019 9:12AM - 9:48AM |
R44.00003: Evidence for Weyl fermions in a heavy fermion semimetal YbPtBi Invited Speaker: Chunyu Guo Materials with non-trivial band topology have been extensively studied in weakly correlated electron systems. Consequently, it is of great interest to test the existence of Weyl fermions when the electronic correlations are strong. Here, we report electronic structure calculations, ARPES, magneto-transport and calorimetric measurements of the canonical heavy fermion semimetal YbPtBi[1], we find triply degenerate points existed in band structure, which split into pairs of Weyl nodes under applying magnetic field. At high temperatures, the chiral anomaly effect is detected in the magneto-transport measurements, which becomes negligible when the electronic correlations become stronger at lower temperatures. However, the topological Hall effect and the temperature dependence of specific heat still demonstrate the existence of Weyl nodes. These results suggest that YbPtBi is a Weyl heavy fermion semimetal, where the bands hosting Weyl nodes are strongly renormalized at low temperatures due to the Kondo effect. Our findings provide a suitable platform to explore the interplay between topology and strong electronic correlations. |
Thursday, March 7, 2019 9:48AM - 10:24AM |
R44.00004: Excitons in topological Kondo insulators: Theory of thermodynamic and transport anomalies in SmB6 Invited Speaker: Johannes Knolle Kondo insulating materials lie outside the usual dichotomy of weakly versus correlated—band versus Mott—insulators. They are metallic at high temperatures but resemble band insulators at low temperatures because of the opening of an interaction-induced band gap. The first discovered Kondo insulator (KI) SmB6 has been predicted to form a topological KI (TKI). However, since its discovery thermodynamic and transport anomalies have been observed that have defied a theoretical explanation. Enigmatic signatures of collective modes inside the charge gap are seen in specific heat, thermal transport, and quantum oscillation experiments in strong magnetic fields. Here, we show that TKIs are susceptible to the formation of excitons and magnetoexcitons. These charge neutral composite particles can account for long-standing anomalies in SmB6. |
Thursday, March 7, 2019 10:24AM - 11:00AM |
R44.00005: Topological Kondo insulators and semimetals Invited Speaker: Onur Erten The electrons in heavy fermion materials experience strong spin-orbit cou- pling interactions that greatly exceed their kinetic energy. It has long been known that the spin-orbit coupling stabilizes new kinds of heavy fermion metals, superconductors and Kondo insulators and semimetals. In this talk, I will discuss the new realization that spin orbit coupling changes the topology leading to new kinds of topological orders. I will mainly focus on SmB6, CeNiSn and time permitting CeSb. In particular, I will discuss the puzzling experimental results on topological Kondo insulators and the possibility of a Skyrme insulating phase in SmB6 [1]. Next I will discuss how non-symmorphic symmetries can lead to Mobius-twisted surface states in failed Kondo insulators[2]. Time permitting, I will discuss recent ARPES experiments on gapless Kondo-Weyl semimetals[3]. |
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