Current-induced atomic dynamics, instabilities, and Raman signals: Quasiclassical Langevin equation approach

Jing-Tao Lu, Mads Brandbyge, Per Hedegard, Tchavdar N. Todorov, Daniel Dundas

Research output: Contribution to journalArticle

64 Citations (Scopus)

Abstract

We derive and employ a semiclassical Langevin equation obtained from path integrals to describe the ionic dynamics of a molecular junction in the presence of electrical current. The electronic environment serves as an effective nonequilibrium bath. The bath results in random forces describing Joule heating, current-induced forces including the nonconservative wind force, dissipative frictional forces, and an effective Lorentz-type force due to the Berry phase of the nonequilibrium electrons. Using a generic two-level molecular model, we highlight the importance of both current-induced forces and Joule heating for the stability of the system. We compare the impact of the different forces, and the wide-band approximation for the electronic structure on our result. We examine the current-induced instabilities (excitation of runaway "waterwheel" modes) and investigate the signature of these in the Raman signals.

Original languageEnglish
Article number245444
Pages (from-to)1-16
Number of pages16
JournalPhysical Review B (Condensed Matter)
Volume85
Issue number24
DOIs
Publication statusPublished - 25 Jun 2012

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

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