Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session S66: Strongly Correlated Topological MetalsInvited
|
Hide Abstracts |
Sponsoring Units: DCMP Chair: Subir Sachdev, Harvard University Room: Four Seasons 1 |
Thursday, March 5, 2020 11:15AM - 11:51AM |
S66.00001: The Weyl-Kondo semimetal Ce3Bi4Pd3 and its field-tuned phase diagram Invited Speaker: Silke Buehler-Paschen The interplay of topology and strong electron correlations is emerging as a new frontier in quantum science; it is expected to bring forth exotic phases and excitations, as epitomized by the example of the fractional quantum Hall effect. Indeed, (weakly interacting) topological semimetals—featuring states with Dirac or Weyl dispersion in the bulk—were discovered when their correlation-driven counterparts were pursued. Heavy fermion systems provide an ideal setting because the Kondo interaction implements extreme correlation strength and representatives with strong spin-orbit coupling exist. A joint effort of experiments and theory has recently led to the discovery of a Weyl-Kondo semimetal phase [1-3]. Experimentally, it is realized in the noncentrosymmetric time reversal symmetry preserving heavy fermion semimetal Ce3Bi4Pd3 [1,3]. This material has a Kondo temperature of 13 K [1] and remains paramagnetic down to at least 250 mK [3]. Our most striking observation is a giant spontaneous (zero-field) Hall effect, and an associated even-in-field Hall component, which provide direct evidence of Berry curvature singularities in close vicinity to the Fermi level [3]. These characteristics of Weyl physics develop only in the Kondo coherent state, and are thus manifestly correlation driven. The application of large magnetic fields leads to an annihilation of the Weyl nodes at a first critical field, and to the metallization of the system at a second one, featuring quantum criticality [4]. |
Thursday, March 5, 2020 11:51AM - 12:27PM |
S66.00002: Weyl-Kondo Semimetal in non-Symmorphic Systems Invited Speaker: Qimiao Si There is considerable current interest to explore electronic topology in strongly correlated metals. A promising setting arises in heavy fermion systems, which may feature not only strong correlations but also a large spin-orbit coupling. Recently, a Weyl-Kondo semimetal phase has been concurrently discovered in theoretical [1] and experimental [2] studies. The theoretical work was carried out in a Kondo lattice model that is time-reversal invariant but inversion-symmetry breaking. The defining characteristics of the Weyl-Kondo semimetal include linearly-dispersing Weyl nodal excitations with highly reduced velocity and the Weyl nodes being pinned to the Fermi energy. In this talk, I will summarize the theoretical developments, with a focus on the effect of non-symmorphic space-group symmetry in conjunction with strong correlations [1,3], the transitions to nearby quantum phases, as well as the efficient control of the Weyl nodes including their annihilation by a magnetic field [4,5]. The enrichment of these results for the global phase diagram of heavy fermion metals, reflecting on the role of spin-orbit coupling in the competion of quantum phases that develop out of the spin degrees of freedom [6], will be discussed. |
Thursday, March 5, 2020 12:27PM - 1:03PM |
S66.00003: From Trivial Kondo Insulator Ce3Pt3Bi4 to Topological Nodal-line Semimetal Ce3Pd3Bi4 Invited Speaker: Chao Cao Using the density functional theory combined with dynamical mean-field theory, we have performed systematic study of the electronic structure and its band topology properties of Ce3Pt3Bi4 and Ce3Pd3Bi4. At high temperatures (∼290K), the electronic structures of both compounds resemble the open-core 4f density functional calculation results. For Ce3Pt3Bi4, clear hybridization gap can be observed below 72K, and its coherent momentum-resolved spectral function below 18K exhibits an topologically trivial indirect gap of ∼6 meV and resembles density functional band structure with itinerant 4f state. For Ce3Pd3Bi4, no clear hybridization gap can be observed down to 4K, and its momentum-resolved spectral function resembles electron-doped open-core 4f density functional calculations. The band nodal points of Ce3Pd3Bi4 at 4K are protected by the gliding-mirror symmetry and form ring-like structure. Therefore, the Ce3Pt3Bi4 compound is topologically trivial Kondo insulator while the Ce3Pd3Bi4 compound is topological nodal-line semimetal. |
Thursday, March 5, 2020 1:03PM - 1:39PM |
S66.00004: Evidence for Undoped Weyl Semimetal Charge Transport in a bad Weyl Semi-Metal: Y2Ir2O7 Invited Speaker: Arthur Ramirez Most Weyl semimetals studied to date either have a chemical potential not situated at the nodal point, or multiple nodal points at different energies, thus leading to metallic behavior in resistivity versus temperature. Undoped Weyl semimetals, in which the chemical potential is exactly at the nodal point will exhibit characteristic non-metallic behavior in transport that should reveal the density of electronic states as well as the dominant scattering mechanisms. We discuss the various types of transport for both doped and undoped Weyl systems. We show that one candidate, Y2Ir2O7, predicted to display a spectrum of an undoped Weyl semimetal, exhibits behavior of a system with the expected quadratic density of states and scattering from charged impurities, namely resistivity varying as 1/T^4 over a large temperature range. We discuss the implications of these results in light of exsiting theories, as well as prospects for future work. |
Thursday, March 5, 2020 1:39PM - 2:15PM |
S66.00005: STM studies of candidate topological Kondo insulator SmB6 Invited Speaker: Steffen Wirth SmB6 has been proposed a topological Kondo insulator with nontrivial surface states inside a bulk hybridization gap. Experimentally, hybridization between localized 4f and conduction band states at low temperatures is well established [1]. Using STM, we performed local measurements on well identified, atomically flat, unreconstructed surfaces [2]. Tunneling spectroscopy down to 0.35 K revealed sharp peak-like features with a strong temperature dependence within the hybridization gap. The features around –6 mV and –2 mV are dominated by surface contributions to the local density of states [3]. These surface states are robust in the vicinity of randomly occurring non-magnetic impurities, while introducing magnetic impurities in samples (Sm1-xRx)B6 with R = Gd influences the surface states on a much larger length scale compared to non-magnetic impurities [4]. |
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