Discovering the auxetic transition driven by the electronic correlation

The auxetic behavior in nanostructures has attracted considerable attention due to their wide potential applications. Due to the long-standing attribution of auxetic properties to the unique geometric structure of materials, the academic community's understanding of auxeticity is not profound. It is considered to have no access to tuning the auxeticity without phase transition. In this letter, an anomalous case is discovered where the auxetic transition is directly driven by the electronic correlation in Janus-Tetra-SiXY (JT-SiXY; X, Y = O, S, Se) lattice. The auxeticity is highly dependent on the electronic properties. Additionally, the auxeticity is significantly enhanced due to the Janus modification. The emerging auxetic transition effect and enhanced auxeticity would make JT-SiXY a promising candidate in two-dimensional nano-devices. Our study provides valuable clues and useful guidance for designing advanced auxetic materials.