Three-gap superconductivity in two-dimensional InB2/InB4 films

In recent years, multigap superconductors have attracted much attention since the discovery of novel two-gap superconductivity with transition temperature T-c similar to 39 K in bulk MgB2. Based on the first-principles calculation and anisotropic Migdal-Eliashberg theory, we conduct a study on a series of two-dimensional (2D) boron-based materials with doped metal atoms to search for multigap superconductors. We find that InB2 monolayer films and InB4 trilayer films are dynamically stable but not synthesized experimentally yet. An evident three-gap superconductor with high T-c similar to 41.5 K is obtained in a InB2 monolayer film. Similarly, InB4 trilayer film is a novel superconductor with three distinct superconducting gaps and a high T-c similar to 53 K. The superconductivity in both 2D films originates mainly from the covalent-state-driven metallization. In addition, the effect of biaxial strain on the superconducting behavior of InB4 trilayer films is also involved. The InB4 trilayer films stay dynamically stable under biaxial tensile strain of -3%-6%, and the highest T-c boosts to 64 K under the biaxial tensile strain of similar to 4%. Meanwhile, we also find that the GeB4 and ZnB4 trilayer films are two-gap superconductors with high T-c similar to 48.5 and 32 K, respectively.

Automated summary

The study focuses on the search for multigap superconductors in two-dimensional boron-based materials doped with metal atoms, resulting in the discovery of stable InB2 and InB4 films with high Tc values of 41.5K and 53K, respectively. Additionally, the superconducting behavior of InB4 films is found to be influenced by biaxial strain, with Tc reaching up to 64K under specific conditions. Other trilayer films like GeB4 and ZnB4 also exhibit high Tc values of 48.5K and 32K, respectively, as two-gap superconductors.