1D-inorganic crystals with atomic-scale helical motifs promise unique properties such as non-centrosymmetric symmetry, chiral-induced spin selectivity, and nonlinear optical activity. In collaboration with the Maxx Arguilia research group (UCI), we discover and characterize a new inorganic compound named gallium sulfur iodide (GaSI), which has a unique helical structure and a “squircular” cross-section and crystallizes in a non-centrosymmetric space group. Density Functional Theory calculations reveal that the squircular helical shape is a thermodynamically stable structure based on their formation energy and dynamic stability at room temperature. DFT predicts that GaSI is a direct bandgap semiconductor, whose bandgap is consistent with the experimental measurement. These findings expand the scope of III−VI−VII van der Waals crystals and open new possibilities for applications in optics, electronics, and chiral-induced phenomena.
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K. Dold , D. Cordova , S. Singsen , J. Nguyen , G. Milligan , M. Marracci , Z. Yao , J. Ziller, D. Fishman , E. M. Y. Lee, and M. Arguilla. “GaSI: A wide gap non-centrosymmetric helical crystal” Journal of the American Chemical Society, 146, 33, 22881–22886, 2024, https://doi.org/10.1021/jacs.4c06487
