Phonons, Instabilities and Origin of Polarization in KDP Crystals

G. Colizzi, Jorge Kohanoff, J. Lasave, R.L. Migoni

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

The -phonons of KH2PO4 (KDP) and its deuterated analog DKDP are studied via first-principles linear response calculations. The paraelectric phase shows two instabilities. One for a z-polarized mode, which leads to the spontaneous polarization Ps of the ferroelectric phase. The other corresponds to a two-fold degenerate xy-polarized mode. Other phonons are analyzed, which couple to the ferroelectric one at large amplitudes and are relevant for the ferroelectric transition. We show that Ps is mainly of electronic nature, since it arises mostly from an off-diagonal component of the Born effective charge tensor of H, with minor contribution from P atoms displacements.
Original languageEnglish
Pages (from-to)200-206
Number of pages7
JournalFerroelectrics
Volume401
Issue number1
DOIs
Publication statusPublished - 2010

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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