Noncontact dissipation reveals critical central peak in SrTiO3

TL;DR

This study demonstrates that noncontact force microscopy can detect critical fluctuations associated with the phase transition in SrTiO3, revealing an intrinsic central peak width much narrower than previously observed by neutron scattering.

Contribution

It provides the first direct measurement of the intrinsic central peak width in SrTiO3 using noncontact dissipation, linking mechanical dissipation to critical fluctuations.

Findings

Noncontact dissipation reveals the antiferrodistortive phase transition.

The intrinsic central peak width is approximately 80 kHz.

The results connect mechanical dissipation to critical fluctuations in the crystal.

Abstract

The critical fluctuations at second order structural transitions in a bulk crystal may affect the dissipation of mechanical probes even if completely external to the crystal surface. Here we show that noncontact force microscope dissipation bears clear evidence of the antiferrodistortive phase transition of SrTiO3, known for a long time to exhibit a unique, extremely narrow neutron scattering "central peak". The noncontact geometry suggests a central peak linear response coupling connected with strain. The detailed temperature dependence reveals for the first time the intrinsic central peak width of order 80 kHz, two orders of magnitude below the established neutron upper bound.