Valley- and Orbital-Controlled 2D Chern Insulators Without Spin-orbit Interaction

Abstract

We present a theoretical study of orbital-induced topological phase transitions in a two-dimensional lattice model with staggered potential $(\hat{I}”)$ and orbital coupling $(\hat{I}»)$ competing with the hopping strength. By tuning these parameters, two gap-closing mechanisms emerge: valley closure at $\mathbf{K}$ and ${\mathbf{K}}^{\prime }$ for $\hat{I}»=\pm \hat{I}”$, and a $\hat{\mathbf{I}}“$-point closure at $\hat{I}»=\pm \sqrt{\hat{I}{”}^2+9t_0^2}$. Their interplay defines a topological window in which the Berry curvature localizes near a single valley, yielding a quantized anomalous Hall conductivity ($\ddot{I}{ƒ}_{xy}=e^2/h$) and Chern number ($C=1$). These results demonstrate orbital-driven Chern insulating behavior without spin-orbit coupling. The resulting phase diagram captures the transition from trivial to topological phases and suggests practical routes for orbital engineering in tunable lattice systems.

8 pages, 5 figures. This manuscript has been transferred from Physics Letters A (Elsevier) for consideration in the arXiv submission