Electric-field-induced topological phase transition in CrS<sub>2</sub>/CrSe<sub>2</sub> heterostructures

Electric fields can induce topological phase transitions from normal insulators to topological insulators, offering a promising pathway for designing low-power electronic devices based on two-dimensional topological insulators with tunable and practical functionalities. In this work, we demonstrate a dynamically tunable topological insulator realized in van der Waals (vdW) heterostructures composed of two-dimensional transition metal dichalcogenides — specifically, a CrS2/CrSe2 junction. Remarkably, this system exhibits significant electric-field tunability of its topological properties. First-principles calculations reveal that an external electric field induces a band inversion at a critical field strength of −2.0 eV/nm, signaling the emergence of nontrivial topological phases. These topological characteristics remain robust, as confirmed by van der Waals-corrected DFT-D2 calculations. Furthermore, we systematically explore strain engineering as an additional control parameter. Under 1.45% biaxial strain, the band inversion threshold shifts significantly to −0.3 eV/nm while maintaining a finite bandgap of 9.6 meV. This dual tunability, achieved through both electric fields and mechanical strain, establishes the CrS2/CrSe2 heterostructure as a versatile platform for developing topological field-effect transistors and other quantum devices requiring dynamic control of edge conduction states.