학술논문
Phonon spectrum of single-crystalline FeSe probed by high-resolution electron energy-loss spectroscopy.
Document Type
Article
Source
Subject
*PHONON spectra
*IRON selenides
*ELECTRON energy loss spectroscopy
*VACUUM
*ANTIFERROMAGNETISM
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Language
ISSN
0921-4534
Abstract
Utilizing high-resolution electron energy-loss spectroscopy (HREELS) we measure the phonon frequencies of β –FeSe(001), cleaved under ultra-high vacuum conditions. At the zone center ( Γ ¯ –point) three prominent loss features are observed at loss energies of about ≃ 20.5 and 25.6 and 40 meV. Based on the scattering selection rules we assign the observed loss features to the A 1 g , B 1 g , and A 2 u phonon modes of β –FeSe(001). The experimentally measured phonon frequencies do not agree with the results of density functional based calculations in which a nonmagnetic, a checkerboard or a strip antiferromagnetic order is assumed for β –FeSe(001). Our measurements suggest that, similar to the other Fe-based materials, magnetism has a profound impact on the lattice dynamics of β –FeSe(001). [ABSTRACT FROM AUTHOR]