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Structurally Driven, Reversible Topological Phase Transition in a Distorted Square Net Material
Xian P Yang1, Chia-Hsiu Hsu2,3, Gokul Acharya4
1Princeton University, Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton, New Jersey, USA.
Abstract:
Topological materials hold immense promise for exhibiting exotic quantum phenomena, yet achieving controllable topological phase transitions remains challenging. Here, we demonstrate a structurally driven, reversible topological phase transition in the distorted square net material GdPS, induced via in situ potassium dosing. Using angle-resolved photoemission spectroscopy and first principles calculations, we demonstrate a cascade of topological phases in the subsurface P layer: from a large, topologically trivial band gap to a gapless Dirac cone state with a 2 eV dispersion, and finally to a two-dimensional topological insulator as inferred from theory. This evolution is driven by subtle structural distortions in the first P layer caused by potassium adsorption, which in turn contribute to the band gap closure and topological phase transition. Furthermore, the ability to manipulate the topology of a subsurface layer in GdPS offers a unique route for exploring and controlling topological states in bulk materials.
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