ELFT HÍRADÓ

[tcsaba <tcsaba AT eik.bme.hu>]

                 M E G H Í V Ó - I N V I T A T I O N

    Seminar Series of the Department of Theoretical Physics at the
           Budapest University of Technology and Economics


                          Judit Romhányi
            (Okinawa Institute of Science and Technology )

      Chernful multiplet excitations in the breathing kagome model

We study the topologically nontrivial multiplet excitations of the 
antiferromagnetic spin-1/2 kagome system with breathing anisotropy. We 
show that in the chiral magnetic ground state the excitations can be 
characterized by a low-energy spin-1/2 doublet and a high-energy 
spin-3/2 quartet. A small magnetic field removes the degeneracy of the 
multiplets and the excitations become topologically nontrivial with 
Chern numbers C_m = 2m, the spin-3/2 manifold thus having large Chern 
numbers -3, -1, 1, 3. Increasing the magnetic field above a critical 
point, the bands undergo a topological transition when a novel spin-3/2 
Dirac cone is formed by the touching of four bands. Above the critical 
field the bands become trivial. Before a similar topological transition 
occurred for the lower spin-1/2 doublet, at a higher magnetic field 
value, a conventional symmetry breaking transition takes place to the 
1/3-plateau phase in which all bands are topologically trivial.


Időpont: 2017. december 22. péntek, 10:15
Helyszín: BME Fizikai Intézet, Elméleti Fizika Tanszék,
Budafoki út 8. F-épület, III lépcsőház, szemináriumi szoba