Superconductivity emerging near quantum critical point of valence transition

TL;DR

This study investigates the quantum valence transition in a one-dimensional model, revealing that superconductivity emerges near the transition due to enhanced electron coherence driven by valence fluctuations.

Contribution

It demonstrates that quantum fluctuations and electron correlations stabilize the valence transition and induce superconductivity in the Kondo regime of the model.

Findings

Superconductivity develops near the valence transition in the Kondo regime.

Quantum fluctuations stabilize the valence crossover and promote electron coherence.

Superconductivity is linked to enhanced charge velocity, not charge compressibility.

Abstract

The nature of the quantum valence transition is studied in the one-dimensional periodic Anderson model with Coulomb repulsion between f and conduction electrons by the density-matrix renormalization group method. It is found that the first-order valence transition emerges with the quantum critical point and the crossover from the Kondo to the mixed-valence states is strongly stabilized by quantum fluctuation and electron correlation. It is found that the superconducting correlation is developed in the Kondo regime near the sharp valence increase. The origin of the superconductivity is ascribed to the development of the coherent motion of electrons with enhanced valence fluctuation, which results in the enhancement of the charge velocity, but not of the charge compressibility. Statements on the valence transition in connection with Ce metal and Ce compounds are given.