Jahn-Teller Solitons, Structural Phase Transitions and Phase Separation

TL;DR

This paper demonstrates that molecular solids with Jahn-Teller interactions can support stable, localized charge solitons that are linked to structural phase transitions and phase separation phenomena.

Contribution

It introduces the concept of Jahn-Teller solitons as stable, non-topological excitations in molecular solids, connecting their stability and divergence to phase transitions.

Findings

Jahn-Teller solitons are stable below a critical coupling strength.

Approaching the critical coupling causes the soliton size to diverge.

Soliton behavior mimics phase separation in complex solids.

Abstract

It is demonstrated that under common conditions a molecular solid subject to Jahn-Teller interactions supports stable Q-ball-like non-topological solitons. Such solitons represent a localized lump of excess electric charge in periodic motion accompanied by a time-dependent shape distortion of a set of adjacent molecules. The motion of the distortion can correspond to a true rotation or to a pseudo-rotation about the symmetric shape configuration. These solitons are stable for Jahn-Teller coupling strengths below a critical value; however, as the Jahn-Teller coupling approaches this critical value, the size of the soliton diverges signaling an incipient structural phase transition. The soliton phase mimics features commonly attributed to phase separation in complex solids.