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 $(\Delta )$ and orbital coupling $(\lambda )$ competing with the hopping strength. By tuning these parameters, two gap-closing mechanisms emerge: valley closure at $\mathbf{K}$ and ${\mathbf{K}}^{\prime }$ for $\lambda =\pm \Delta$, and a $\mathbf{\Gamma }$-point closure at $\lambda =\pm \sqrt{{\Delta }^2+9t_0^2}$. Their interplay defines a topological window in which the Berry curvature localizes near a single valley, yielding a quantized anomalous Hall conductivity (${\sigma }_{xy}=e^2/h$) 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

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