Role of Ward-Takahashi identity in an electron-phonon coupled system -- Revisiting phonon shift current

Fuente: arXiv
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Main Authors: Morimoto, Takahiro, Nagaosa, Naoto
Format: Preprint
Published: 2025
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author Morimoto, Takahiro
Nagaosa, Naoto
author_facet Morimoto, Takahiro
Nagaosa, Naoto
contents We study bulk photovoltaic effects in electron-phonon coupled systems. The conservation of current or gauge invariance, manifested as the Ward-Takahashi identity, plays an essential role in the analysis of the Feynman diagrams, and the leading order contribution to the phonon shift current is identified accordingly. The leading order contribution essentially arises from the electric polarization carried by optically excited phonons, where the shift current is generated due to a change of electric polarization in the steady state under the optical excitation of phonons.
format Preprint
id arxiv_https___arxiv_org_abs_2508_15347
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Role of Ward-Takahashi identity in an electron-phonon coupled system -- Revisiting phonon shift current
Morimoto, Takahiro
Nagaosa, Naoto
Strongly Correlated Electrons
We study bulk photovoltaic effects in electron-phonon coupled systems. The conservation of current or gauge invariance, manifested as the Ward-Takahashi identity, plays an essential role in the analysis of the Feynman diagrams, and the leading order contribution to the phonon shift current is identified accordingly. The leading order contribution essentially arises from the electric polarization carried by optically excited phonons, where the shift current is generated due to a change of electric polarization in the steady state under the optical excitation of phonons.
title Role of Ward-Takahashi identity in an electron-phonon coupled system -- Revisiting phonon shift current
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2508.15347