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  • [APCTP SEMINAR] Magnetic Topological Quantum Chemistry
  • 작성자 관리자 등록일 2020-10-06 조회수 40
  • VENUE Online via ZOOM
     

    PERIOD Oct. 23 (Fri.), 2020 / 10:00 AM – 11:00 AM (KST)

     

    ABSTRACT
     Over the last 100 years, the group-theoretic characterization of crystalline solids has provided the foundational language for diverse problems in physics and chemistry.  There exist two classes of crystalline solids: non-magnetic crystals left invariant by space groups (SGs), and  solids with commensurate magnetic order that respect the symmetries of magnetic space groups (MSGs). Whereas many of the properties of the SGs, such as their momentum-space corepresentations (coreps) and elementary band coreps (EBRs) were tabulated with relative  ease, progress on deriving the analogous properties of the MSGs has largely stalled for the past 70 years due to the complicated symmetries of magnetic crystals. In the works discussed in this talk, we have completed the 100-year-old problem of crystalline group theory by deriving the small coreps, momentum stars, compatibility relations, and magnetic EBRs (MEBRs) of the single (spinless) and double (spinful) MSGs. We have implemented freely-accessible tools on the Bilbao Crystallographic Server for accessing the coreps of the MSGs, whose wide-ranging applications include neutron diffraction investigations of magnetic structure and characterizing time-reversal-breaking superconducting order, the interplay of lattice regularization and (symmetry-enhanced) fermion doubling, and magnetic topological phases. Using the MEBRs, we have extended the earlier theory of Topological Quantum Chemistry to the MSGs to form a complete, real-space theory of band topology in magnetic and nonmagnetic crystalline solids -- Magnetic Topological Quantum Chemistry (MTQC). We then used MTQC to derive the complete set of symmetry-based indicators (SIs) of band topology in all spinful (fermionic) crystals, for which we have identified symmetry-respecting bulk and anomalous surface and hinge states. Lastly, using the SIs, we have discovered several novel non-axionic magnetic higher-order topological insulators.  Time permitting, I will also briefly discuss our work applying MTQC to the search for novel magnetic topological materials.

     

     References

    [1] “Magnetic Topological Quantum Chemistry,” L. Elcoro*, B. J. Wieder*, Z.-D. Song, Y. Xu, B. Bradlyn, and B. Andrei Bernevig, Submitted (to appear on the arXiv on Sunday, Oct. 4, 2020).

    [2] “High-Throughput Calculations of Antiferromagnetic Topological Materials from Magnetic Topological Quantum Chemistry,” Y. Xu, L. Elcoro, Z.-D. Song, B. J. Wieder, M. G. Vergniory, N. Regnault, Y. Chen, C. Felser, and B. Andrei Bernevig,  arXiv:2003.00012 (2020) [to appear in Nature]. 

     

    INVITED SPEAKER

      
     

    ORGANIZER

     

    SPONSOR
    APCTP
     

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