Enhancement of superconductivity and its relation to lattice expansion in InxTe (0.84≤x≤1)

The quest to govern the driving forces behind superconductivity and gain control over the superconducting transition temperature T-c is as old as the phenomenon itself. Microscopically, this requires a proper understanding of the evolution of electron-lattice interactions in their parameter space. We report such a controlled study on T-c in InxTe via fine-tuning the In stoichiometry x. We find that increasing x from 0.84 to 1 results in an enhancement of T-c from 1.3 K to 3.5 K accompanied by an increase of the electron-phonon coupling constant from 0.45 to 0.63. Employing first-principles calculations, we show that this behavior is driven by two factors, each taking the dominant role depending on x. For x less than or similar to 0.92, the major role is played by the density of electronic states at the Fermi level. Above x similar to 0.92, the change in the density of states flattens while the enhancement of T-c continues. We attribute this to a systematic softening of lattice vibrations, amplifying the electron-phonon coupling, and hence, T-c.

Automated summary

This study investigates the changes in the superconducting temperature in InxTe by fine-tuning the stoichiometry of indium. The results show that increasing the indium content leads to an enhancement in the superconducting temperature and the electron-phonon coupling constant. First-principles calculations reveal that this behavior is driven by two factors, with different factors dominating depending on the indium content.