Joint regulation mechanism of atomic occupation and composition on superconductivity of S-P binary cubic superconductors

Light element binary compounds are highly promising candidates for superconductivity. Based on first-principles calculations, this paper studies seven sulfur-phosphorus compounds with the same configuration but different site occupation, and determines their minimum stable pressure within the range of 0-200 GPa. Among them, SP-I, SP-II and S 5 P 3 -I, S 5 P 3 -II are isomeric structures with the same chemical formula, but only the atomic site occupation is different, resulting in a 5.22 K and 1.49 K difference in superconducting properties. The study confirms that the atomic site occupation and chemical composition jointly regulate superconducting properties. Under a fixed chemical ratio, the core factor controlling T c is determined by the α 2 F(ω) spectral distribution of the site occupation, which is determined by the sublattice positions occupied by each structure around the Fermi level. This provides a new idea for the structural design and performance optimization of light element superconducting materials.