Surface phonons of NiO(001) ultrathin films grown pseudomorphically on Ag(001)

SURFACE SCIENCE

卷:643

Article

Kostov, K. L.^1,2  Polzin, S.¹  Schumann, F. O.¹  Widdra, W.^1,3 

[1] Univ Halle Wittenberg, Inst Phys, D-06120 Halle, Germany

[2] Bulgarian Acad Sci, Inst Gen & Inorgan Chem, BU-1113 Sofia, Bulgaria

[3] Max Planck Inst Microstruct Phys, D-0120 Halle, Germany

关键词: Vibrational spectroscopy;    Surface phonons;    Oxide thin film;    Nickel oxide;   

DOI  :  10.1016/j.susc.2015.08.022

来源: Elsevier

【 摘 要 】

For an ultrathin NiO(001) film of 4 monolayer (ML) thickness grown on Ag(001), the vibrational properties have been determined by high-resolution electron energy loss spectroscopy (HREELS). For the well-ordered pseudomorphically grown film, nine phonon modes have been identified and their dispersions have been revealed along the (Gamma) over bar(X) over bar high-symmetry direction. The comparison with phonon data for a 25 ML thick NiO(001) film shows that the NiO(001) phonon properties are already fully developed at 4 ML Significant differences are found for the surface-localized phonon S-6 which has an increased dispersion for the ultrathin film. The dipole-active Fuchs-Kliewer phonon-polariton exhibits a narrower lineshape than the mode found for a single-crystal surface, which might hint to a reduced antiferromagnetic coupling in the ultrathin film. (C) 2015 Elsevier B.V. All rights reserved.

【 授权许可】

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