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TT: Fachverband Tiefe Temperaturen
TT 94: Correlated Magnetism – Low-Dimensional Systems
TT 94.9: Vortrag
Freitag, 13. März 2026, 11:45–12:00, HSZ/0101
Electric-field-driven flat band in a distorted generalized sawtooth chain — •Vadim Ohanyan1, 2, Lusik Amiraghyan1,3, Michael Sekania4,5, and Marcus Kollar6 — 1Laboratory of Theoretical Physics, Yerevan State University, 1 Alex Manoogian, 0025 Yerevan, Armenia — 2CANDLE, Synchrotron Research Institute, 31 Acharyan Str., 0040 Yerevan, Armenia — 3Institute of Applied Problems of Physics, 25 Hr. Nersisyan St, Yerevan 0014, Armenia — 4Rechenzentrum, University of Augsburg, 86135 Augsburg, Germany — 5Andronikashvili Institute of Physics, Javakhishvili Tbilisi State University, Tamarashvili str. 6, 0177 Tbilisi, Georgia — 6Theoretical Physics III, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, 86135 Augsburg, Germany
We investigate flat magnon bands in a sawtooth chain where symmetric exchange, DM interaction, and axial anisotropy differ on each side of the triangular plaquette. When the DM terms arises from the Katsura-Nagaosa-Balatsky (KNB) magnetoelectric mechanism, the corresponding DM coefficients become functions of the electric field and the lattice geometry. This dependence is governed by two bond angles, which become inequivalent under a distortion of the triangular plaquette. We derive the conditions under which an electric field, aligned along the lattice bonds, drives the one-magnon spectrum into a flat-band regime. The distortion angle dependence of the saturation field is examined as well. We construct a mapping from flat-band solution obtained for a general DM interaction into those arising from its KNB-induced form.
Keywords: Sawtooth chain; localized magnons; Dzyaloshinskii-Moriya interaction; Katsura-Nagaosa-Balatsky mechanism