Dynamic elastic response of KMn(1-x)Ca(x)F(3): Elastic softening and domain freezing

Wilfried Schranz, Peter Sondergeld, Andri V Kityk, Ekhard K H Salje

Veröffentlichungen: Beitrag in FachzeitschriftArtikelPeer Reviewed


Results of continuous-wave resonance (MHz-region) and ultralow-frequency (Hz-region) dynamic mechanical analyzer measurements of pure KMnF(3) and mixed crystals KMn(1-x)Ca(x)F(3) (x <0.017) are presented in a broad temperature range including the phase-transition regions. The elastic anomalies depend strongly on the measurement frequency: The MHz-elastic constants can be well fitted by Landau theory including the difference between isothermal and adiabatic behavior. Contrary, at low frequencies (0.1-50 Hz) an elastic softening (superelasticity) due to domain-wall motion is found quite similar to that observed recently in isostructural SrTiO(3) [A. V. Kityk , Phys. Rev. B 61, 946 (2000)]. However, unlike to SrTiO(3), for the mixed system KMn(1-x)Ca(x)F(3) we have measured freezing of the domain-wall movement around 100 K in a certain range of concentration of Ca(2+) ions (x=0.003). Calculating the dynamic elastic response to the ac-stress field by taking into account the motion of randomly pinned ferroelastic domain walls in KMn(1-x)Ca(x)F(3) yields excellent agreement between theory and experiment.
FachzeitschriftPhysical Review B
PublikationsstatusVeröffentlicht - 2009

ÖFOS 2012

  • 103009 Festkörperphysik
  • 103008 Experimentalphysik
  • 103029 Statistische Physik
  • 103002 Akustik