Bulletin of the American Physical Society
Joint Fall 2017 Meeting of the Texas Section of the APS, Texas Section of the AAPT, and Zone 13 of the Society of Physics Students
Volume 62, Number 16
Friday–Saturday, October 20–21, 2017; The University of Texas at Dallas, Richardson, Texas
Session E4: Condensed Matter Physics II |
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Chair: Mark Lee, University of Texas at Dallas Room: DGAC 1.128 |
Friday, October 20, 2017 4:15PM - 4:27PM |
E4.00001: Topological Triply-Degenerate Points Induced by Spin-Tensor-Momentum Couplings Haiping Hu, Junpeng Hou, Fan Zhang, Chuanwei Zhang The recent discovery of triply-degenerate points (TDPs) in topological materials has opened a new perspective toward the realization of novel quasiparticles without counterparts in quantum field theory. The emergence of such protected nodes is often attributed to spin-vector-momentum coupling (SVMC). Here we show that the interplay between spin-tensor-momentum coupling (STMC) and SVMC can induce three types of TDPs, classified by their different Chern numbers ($\mathcal{C}=\pm 2,\pm 1,0$). Under a Zeeman field, type-I ($\mathcal{C}=\pm 2$) and type-II ($\mathcal{C}=\pm 1$) TDPs can be lifted into two Weyl points carrying the same and opposite monopole charges, respectively, whereas a type-III ($\mathcal{C}=0$) TDP is broken into two pairs of Weyl points of opposite charges. We find that different TDPs of the same type are connected by intriguing Fermi arcs on surfaces, and that transitions between different types are accompanied by level crossings along high-symmetry lines. We further propose an experimental scheme for realizing such TDPs in cold-atom optical lattices. Our results provide a framework for studying STMC-induced TDPs and other exotic quasiparticles. [Preview Abstract] |
Friday, October 20, 2017 4:27PM - 4:39PM |
E4.00002: Majorana Corner States of Topological Edge Superconductors Qiyue Wang, Fan Zhang Majorana bound states often occur at an end of a topological superconductor or at the Pi Josephson Junction mediated by a helical edge state. Here we show that there can emerge one Majorana Kramers pair at a corner of a finite-size quantum spin Hall insulator proximity coupled to an extended s-wave superconductor. We obtain a phase diagram that emphasizes the roles of chemical potential, order parameters, and edge orientations. Our scheme offers a unique platform and opens a new perspective for exploring non-Abelian quasiparticles and topological quantum computing. [Preview Abstract] |
Friday, October 20, 2017 4:39PM - 4:51PM |
E4.00003: Quantum Hall Charge Kondo Criticality Zhi-qiang Bao, Fan Zhang The long-thought charge Kondo effects have recently been experimentally realized in the quantum Hall regime. This experiment, supported by numerics, exemplifies the realization of two-channel Kondo state, a non-Fermi Liquid, and its crossover to the one-channel counterpart, a Fermi liquid. Scaling up such a platform, we find a hierarchy of non-Fermi Liquids and their tunable crossovers based on a renormalization group analysis. Utilizing results from a conformal field theory, we further examine the universal conductances of this strongly correlated system and their finite temperature scaling, which elucidate the sharp distinctions between charge and spin Kondo physics. [Preview Abstract] |
Friday, October 20, 2017 4:51PM - 5:03PM |
E4.00004: Nematic, Ferroelectric, Quantum Hall States in Odd-layer Transition Metal Dichalcogenides Patrick Cheung, Fan Zhang Three-fold rotational symmetry in transition metal dichalcogenides (TMDCs) leads to three elliptical electron pockets, with each of them centered at $Q$, a region between $\Gamma$ and $K$ in the momentum space. When this odd-layer triple-valley system is subject to a perpendicular magnetic field, spontaneous rotational symmetry breaking occurs when the lowest Landau levels are 1/3 or 2/3 filled. The resulting nematic state and the lack of inversion center for each pocket lead to a spontaneous electric polarization. This ferroelectric characteristic makes manipulation of electrons into a preferred single valley-polarized state by an applied electric field possible. [Preview Abstract] |
Friday, October 20, 2017 5:03PM - 5:15PM |
E4.00005: Prediction of novel magnetic materials Saeed Rahmanian koshkaki, Artem Oganov, Saeed Rahmanian koshkaki, Qian Guang-Rui Discovery of new magnetic materials is a big challenge to modern material science. In this presentation, we attempt to report our results in the discovery of new hard magnetic materials candidate, with no rare earth elements in their chemical formula. Besides this, we also investigated the effect of electron correlation on the thermodynamic stability of materials by means of DFT calculation. To predict hard magnet, We utilized the state of art algorithm, USPEX, and then we used the micro-magnet model to compute hard magnetic properties of predicted materials. Searches were performed at zero pressure using GGA and GGA+U (to account for correlation effects). Successfully, we predicted new hard magnet candidates, with a perfect agreement between predicted crystal structure and experimental data, but the magnetic properties yet to be confirmed experimentally. [Preview Abstract] |
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