Enhancement of superconductivity and its relation to lattice expansion in InTe

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 In x Te 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 . 0 . 92, the major role is played by the density of electronic states at the Fermi level. Above x ∼ 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 . This Supplement provides additional data on In x Te.

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