Zigzag nanoribbons of two-dimensional hexagonal crystals: magnetic, topological and thermoelectric properties

Effects of electron-electron and spin-orbit interactions on the ground-state magnetic configuration and on the corresponding thermoelectric and spin thermoelectric properties in zigzag nanoribbons of two-dimensional hexagonal crystals are analyzed theoretically. Thermoelectric properties of quasi-stable magnetic states are also considered. Of particular interest is the influence of Coulomb and spin-orbit interactions on the topological edge states and on the transition between the topological insulator and conventional gap insulator states. It is shown that the interplay of both interactions has also a significant impact on transport and thermoelectric characteristics of the nanoribbons. The spin-orbit interaction additionally determines an in-plane magnetic easy axis. Thermoelectric properties of the nanoribbons with in-plane magnetic moments are compared with those of the nanoribbons with edge magnetic moments oriented perpendicularly to their plane. Nanoribbons with ferromagnetic alignment of the edge moments are shown to reveal spin thermoelectricity, in addition to the conventional one.