Tuning the Flat Band in Bi<sub>2</sub>O<sub>2</sub>Se by Pressure to Induce Superconductivity
Hui Tian, Teng Tu, Xilian Jin, Chenyi Li, Tao Lin, Qing Dong, Xiaoling Jing, Бо Лю, Бо Лю, Ran Liu, Da Li, Zhongkai Liu, Quanjun Li, Hailin Peng, Bingbing Liu, Bingbing Liu
Abstract
The discovery of superconductivity in twisted bilayer graphene has reignited enthusiasm in the field of flat-band superconductivity. However, important challenges remain, such as constructing a flat-band structure and inducing a superconducting state in materials. Here, we successfully achieved superconductivity in Bi 2 O 2 Se by pressure-tuning the flat-band electronic structure. Experimental measurements combined with theoretical calculations reveal that the occurrence of pressure-induced superconductivity at 30 GPa is associated with a flat-band electronic structure near the Fermi level. Moreover, in Bi 2 O 2 Se, a van Hove singularity is observed at the Fermi level alongside pronounced Fermi surface nesting. These remarkable features play a crucial role in promoting strong electron–phonon interactions, thus potentially enhancing the superconducting properties of the material. These findings demonstrate that pressure offers a potential experimental strategy for precisely tuning the flat band and achieving superconductivity.