Victor J. Emery and recent applications of his ideas

TL;DR

This paper reviews Victor Emery's foundational work on one-dimensional electronic systems, highlighting recent discoveries such as ferroelectricity and charge disproportionation in organic compounds, and discusses the resulting complex phenomena like solitons and structural instabilities.

Contribution

It synthesizes Emery's theoretical contributions with recent experimental findings, emphasizing the unification of diverse phenomena in low-dimensional conductors.

Findings

Discovery of ferroelectricity and charge disproportionation in (TMTTF)2X compounds

Observation of various solitons carrying charge and spin

Identification of multiple phenomena like 4kF anomalies and Mott-Hubbard states

Abstract

Victor Emery made seminal contributions to the theory of one-dimensional electronic systems and to its applications to organic metals. His inventions became illuminated recently when the joint effect of the ferroelectricity and the charge disproportionation has been discovered in (TMTTF)2X compounds and beyond. Several of his contributions came to agenda at once: separate gaps in spin/charge channels and the route to solitons, 4kF anomaly, dimerization gap, role of ionic transitions. New phenomena unify an unusual variety of concepts: ferroelectricity of good conductors, structural instability towards Mott-Hubbard state, Wigner crystallization in a dense electronic system, ordered 4kF density wave, richness of physics of solitons, interplay of structural and electronic symmetries. The ferroelectric state gives rise to several types of solitons carrying the electron charge, a noninteger charge, spin or both the spin and the charge in special cases. They are clearly observed via conductivity, electric and magnetic susceptibilities. Solitons are challenging for optics where they already seem to determine the pseudogap in absorption. Various features also appear, or are expected, from collective electronic and coupled electron-phonon modes. The last topic, as well as some aspects of physics of solitons, recalls also the contributions of M.J. Rice. Moreover, the observation of Mott-Hubbard states refers to classical results of A.A. Ovchinnikov.