Vibrational modes of negatively charged silicon-vacancy centers in diamond from ab initio calculations

Elisa Londero, Gergo Thiering, Lukas Razinkovas, A. Gali, Audrius Alkauskas

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Silicon-vacancy (SiV) center in diamond is a photoluminescence (PL) center with a characteristic zero-phonon line energy at 1.681 eV that acts as a solid-state single-photon source and, potentially, as a quantum bit. The majority of the luminescence intensity appears in the zero-phonon line; nevertheless, about 30% of the intensity manifests in the phonon sideband. Since phonons play an essential role in the operation of this system, it is of importance to understand the vibrational properties of the SiV center in detail. To this end, we carry out density functional theory calculations of dilute SiV centers by embedding the defect in supercells of a size of a few thousand atoms. We find that there exist two well-pronounced quasilocal vibrational modes (resonances) with A2u and Eu symmetries, corresponding to the vibration of the Si atom along and perpendicular to the defect symmetry axis, respectively. Isotopic shifts of these modes explain the isotopic shifts of prominent vibronic features in the experimental SiV PL spectrum. Moreover, calculations show that the vibrational frequency of the A2u mode increases by about 30% in the excited state with respect to the ground state, while the frequency of the Eu mode increases by about 5%. These changes explain experimentally observed isotopic shifts of the zero-phonon-line energy. We also emphasize possible dangers of extracting isotopic shifts of vibrational resonances from finite-size supercell calculations, and instead propose a method to do this correctly.

Original languageEnglish
Article number035306
JournalPhysical Review B
Volume98
Issue number3
DOIs
Publication statusPublished - Jul 27 2018

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Diamond
Silicon
Vacancies
vibration mode
Diamonds
diamonds
shift
silicon
Photoluminescence
photoluminescence
Atoms
Defects
defects
symmetry
Vibrational spectra
Phonons
sidebands
Excited states
embedding
Ground state

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Vibrational modes of negatively charged silicon-vacancy centers in diamond from ab initio calculations. / Londero, Elisa; Thiering, Gergo; Razinkovas, Lukas; Gali, A.; Alkauskas, Audrius.

In: Physical Review B, Vol. 98, No. 3, 035306, 27.07.2018.

Research output: Contribution to journalArticle

Londero, Elisa ; Thiering, Gergo ; Razinkovas, Lukas ; Gali, A. ; Alkauskas, Audrius. / Vibrational modes of negatively charged silicon-vacancy centers in diamond from ab initio calculations. In: Physical Review B. 2018 ; Vol. 98, No. 3.
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