Spin excitations in K2Fe4+xSe5: Linear response approach

TitleSpin excitations in K2Fe4+xSe5: Linear response approach
Publication TypeJournal Article
Year of Publication2012
AuthorsKe LQ, van Schilfgaarde M, Antropov V
Journal TitlePhysical Review B
Volume86
Pages020402
Date Published07
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberWOS:000306468400001
Keywordsexchange interactions, superconductors, waves
Abstract

Using ab initio linear response techniques we calculate spin-wave spectra in K2Fe4+xSe5, and find them to be in excellent agreement with a recent experiment. The spectrum can be described reasonably well by a localized spin Hamiltonian restricted to first and second nearest neighbor couplings. We confirm that exchange coupling between nearest neighbor Fe magnetic moments is strongly anisotropic, and show directly that in the ideal system this anisotropy has an itinerant nature which can be imitated by introducing higher order terms in the effective localized spin Hamiltonian (biquadratic coupling). In the real system, structural relaxation provides an additional source of the exchange anisotropy of approximately the same magnitude. The dependence of spin-wave spectra on the filling of Fe vacancy sites is also discussed.

URL<Go to ISI>://WOS:000306468400001
DOI10.1103/PhysRevB.86.020402
Alternate JournalPhys. Rev. B