Polaron with quadratic electron-phonon interaction

Author(s)

Stefano Ragni, Thomas Hahn, Zhongjin Zhang, Nikolay Prokof'ev, Anatoly Kuklov, Serghei Klimin, Matthew Houtput, Boris Svistunov, Jacques Tempere, Naoto Nagaosa, Cesare Franchini, Andrey S. Mishchenko

Abstract

We present a numerically exact study of a polaron with quadratic coupling to the oscillator displacement, or X2 polaron, using two alternative methodological developments. Our results cover both antiadiabatic and adiabatic regimes and the entire range of electron-phonon coupling g2, from the system's stability threshold at attractive g2=-1 to arbitrary strong repulsion at g2≫1. The key properties of X2 polarons prove dramatically different from their linear counterparts. They (i) are insensitive even to large quadratic coupling except in the antiadiabatic limit near the threshold of instability at attraction, (ii) depend only on the adiabatic ratio but are insensitive to the electron dispersion and dimension of space, and (iii) feature weak lattice deformations even at the instability point. Our results are of direct relevance to the properties of electrons at low densities in polar materials, including recent proposals for their superconducting states.

Organisation(s)

Computational Materials Physics

External organisation(s)

University of Massachusetts, Amherst, City University of New York, University of Antwerp, Shanghai Jiao Tong University, Ulmer Fundamental Symmetries Laboratory, University of Tokyo, University of Bologna

Journal

Physical Review B

Volume

107

No. of pages

5

ISSN

2469-9950

DOI

https://doi.org/10.1103/PhysRevB.107.L121109

Publication date

03-2023

Peer reviewed

Yes

Austrian Fields of Science 2012

103015 Condensed matter, 103018 Materials physics

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials, Condensed Matter Physics

Portal url

https://ucris.univie.ac.at/portal/en/publications/polaron-with-quadratic-electronphonon-interaction(99b4fa71-d9d0-40de-a2e8-9d904f500e34).html