Quantum criticality in a uniaxial organic ferroelectric

S. E. Rowley, M. Hadjimichael, M. N. Ali, Y. C. Durmaz, J. C. Lashley, R. J. Cava, J. F. Scott

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16 Scopus citations

Abstract

Tris-sarcosine calcium chloride (TSCC) is a highly uniaxial ferroelectric with a Curie temperature of approximately 130 K. By suppressing ferroelectricity with bromine substitution on the chlorine sites, pure single crystals were tuned through a ferroelectric quantum phase transition. The resulting quantum critical regime was investigated in detail and was found to persist up to temperatures of at least 30-40 K. The nature of long-range dipole interactions in uniaxial materials, which lead to non-analytical terms in the free-energy expansion in the polarization, predict a dielectric susceptibility varying as 1/T 3close to the quantum critical point. Rather than this, we find that the dielectric susceptibility varies as 1/T 2 as expected and observed in better known multi-axial systems. We explain this result by identifying the ultra-weak nature of the dipole moments in the TSCC family of crystals. Interestingly, we observe a shallow minimum in the inverse dielectric function at low temperatures close to the quantum critical point in paraelectric samples that may be attributed to the coupling of quantum polarization and strain fields. Finally, we present results of the heat capacity and electro-caloric effect and explain how the time dependence of the polarization in ferroelectrics and paraelectrics should be considered when making quantitative estimates of temperature changes induced by applied electric fields.

Original languageEnglish (US)
Article number395901
JournalJournal of Physics Condensed Matter
Volume27
Issue number39
DOIs
StatePublished - Sep 11 2015

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics

Keywords

  • electro-caloric, dipoledipole interactions
  • ferroelectric
  • low temperature
  • quantum criticality
  • quantum phase transitions
  • self-consistent phonon theory

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    Rowley, S. E., Hadjimichael, M., Ali, M. N., Durmaz, Y. C., Lashley, J. C., Cava, R. J., & Scott, J. F. (2015). Quantum criticality in a uniaxial organic ferroelectric. Journal of Physics Condensed Matter, 27(39), [395901]. https://doi.org/10.1088/0953-8984/27/39/395901