Abstract:We review a recent progress of a superconductivity and a charge Kondo effect mediated by valence skippers which are elements skipping the valence state. To understand the valence skipping phenomenon, we introduce a negative-U effect phenomenologically, and we show an origin of the negative-U effect, a superconductivity and charge Kondo effect based on the negative-U effect. We also show a new mechanism in which the valence skipping phenomenon and charge Kondo effect are understood unifiedly by the pair hopping… Show more
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