Regensburg 2025 – scientific programme

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MA: Fachverband Magnetismus

MA 15: Poster I

MA 15.33: Poster

Tuesday, March 18, 2025, 10:00–12:30, P1

Flat bands and megnetoelectric effect in XX sawtooth chain with three-spin interactions — •Karen Baghdasaryan¹, Vadim Ohanyan^2,3, Ostap Baran⁴, and Oleg Derzhko⁴ — ¹Ludwig-Maximilians-Universität, München, Germany — ²Yerevan State University, Yerevan, Armenia — ³CANDLE Synchrotron Research Institute, Yerevan, Armenia — ⁴Institute for Condensed Matter Physics, Lviv, Ukraine

We present an exact analysis of the XX sawtooth chain with three-spin interactions and the Katsura-Nagaosa-Balatsky (KNB) mechanism. Using Jordan-Wigner fermionization, we identify all zero-temperature phases of the model and observe the emergence of a flat band in the free-fermion spectrum. These flat bands result in jumps in observables such as magnetization and dielectric polarization as functions of both magnetic and electric fields.

Keywords: Sawtooth chain; Jordan-Wigner fermionization; Flat bands; Katsura-Nagaosa-Balatsky mechanism