The perfect soft mode: giant phonon instability in a ferroelectric

R. Mackeviciute*, M. Ivanov, J. Banys, Nikola Novak, Zdravko Kutnjak, Magdalena Wencka, J. F. Scott

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Previous studies of unstable ('soft') optical modes in ferroelectrics have reported minimum frequencies of 1 cm(-1) (30 GHz) for underdamped phonons. In this work we fabricate a cylindrical coaxial specimen and rectangular plate waveguide specimens of tris-sarcosine calcium chloride (TSCC) and follow its soft mode several orders of magnitude lower to 1 GHz. Below 30 GHz the relaxation time is probably characteristic of domain wall motion; the new theory of Pakhomov et al (2013 Ferroelectrics at press) predicts 0.5 THz far from T-C and a (T - T-C)/T-C dependence, in agreement with our experimental values. This discovery has implications for GHz electronics such as phased array radar or other voltage-tunable low-loss components. The mean-field frequency description of the soft mode response f(T) is supported via precision calorimetry on TSCC with and without Br-doping. The ferroelectric-antiferroelectric phase transition, previously suggested from high-pressure data, is confirmed at 45 K at 1 atm.

Original languageEnglish
Article number212201
Number of pages5
JournalJournal of Physics: Condensed Matter
Volume25
Issue number21
DOIs
Publication statusPublished - 29 May 2013

Keywords

  • SARCOSINE CALCIUM-CHLORIDE
  • TRANSLATIONAL VIBRATIONS
  • DIELECTRIC MEASUREMENTS
  • LIGHT-SCATTERING
  • TRANSITION
  • PHASE
  • TSCC

Fingerprint

Dive into the research topics of 'The perfect soft mode: giant phonon instability in a ferroelectric'. Together they form a unique fingerprint.

Cite this