Speaker
Description
We investigate a paradigmatic model of a frustrated spin system - the sawtooth chain with magnetoelectric coupling - realized through the Katsura-Nagaosa-Balatsky (KNB) mechanism. While an applied magnetic field influences the spin system via the conventional Zeeman term, the electric field couples to the spins through the KNB mechanism, effectively manifesting as a Dzyaloshinskii-Moriya interaction. This interaction depends on the magnitude and direction of the electric field, as well as the geometry of the lattice. In our previous work [1], we demonstrated that an appropriately applied electric field can drive the spin system into a flat-band scenario, thereby circumventing the need for fine-tuned exchange couplings. Specifically, when the electric field is aligned along the basal line of the chain, the saturation magnetic field is reduced. Here, we find that the system exhibits a magnetization jump induced by the electric field, as well as a polarization jump driven by the magnetic field, highlighting a strong magnetoelectric response and an enhanced electrocaloric effect. Furthermore, by considering a generalized sawtooth chain with lattice structure asymmetry, we uncover additional ways to induce a flat-band regime in the one-magnon spectrum through special selection of the electric field’s direction and magnitude.
References
[1] J. Richter et al., “Electric field driven flat bands: Enhanced magnetoelectric and electrocaloric effects in frustrated quantum magnets,” Physical Review B, vol. 105, no. 5. American Physical Society (APS), Feb. 18, 2022. https://doi.org/10.1103/physrevb.105.054420
