Elastic Anomalies in the Quantum Paraelectric Regime of SrTiO ₃

Abstract

Following the proposal by Miiller, Berlinger and Tosatti on a possible coherent quantum regime in SrTiOs below 40K we have performed elastic measurements to look for possible related anomalies in a near-monodomain crystal. The known anomalies related to the 105 K structural transition were well reproduced. In addition, distinct anomalies were observed below 40 K, both in internal friction and in elastic compliance. The anomalies cannot be explained by phonon interaction with the soft TO mode. A different kind of excitation seems to be required.The features found bear some qualitative resemblance to what is observed in the superfluid phase of 4He.

Elastic properties of SrTiO3 crystals at ultralow frequencies

“…Figures 1 and 2 present these parameters in comparison with published experimental data (Rehwald, 1970;Nes et al, 1992;Scott and Ledbetter, 1997).…”

“…The temperature dependences of the elastic constants of SrTi03 were studied with ultrasonic methods by several authors (Rehwald, 1970;Nes et al, 1992;Scott and Ledbetter, 1997). This work analyses these results in terms of the free energy expansion of Salje ef al.…”

A combined X-ray diffraction and Raman scattering study of the phase transitions in Sr1−xCaxTiO3 (x=0.04, 0.06, and 0.12)

“…Quantum fluctuations, however, preclude the condensation of this soft mode below 4 K as a result of which the dielectric constant shows saturation below 4 K [1]. SrTiO 3 is therefore termed as an incipient ferroelectric down to T % 0 K. There is also the possibility [4][5][6][7][8] of a quantum phase transition into a coherent quantum state below 36 K similar to that in liquid He II [9].…”

Domains within Domains and Walls within Walls: Evidence for Polar Domains in CryogenicSrTiO3

“…[2]); these are now viewed as arising from more pedestrian origins and not super at all. Shortly thereafter Courtens et al [3,4], based upon a small unexplained splitting in transverse acoustic phonon energies, proposed the existence of second sound in the same temperature range [5], the present consensus is that this arises from small displacements of Sr ions along [111] directions that lower the tetragonal symmetry below $70 K and remove vibrational mode degeneracies.…”