SrTiO3 displacive transition revisited via coherent X-ray diffraction

Area of Science:

• Materials Science
• Condensed Matter Physics
• Crystallography

Background:

• Strontium titanate (SrTiO3) is a prototypical material for studying displacive phase transitions.
• Critical fluctuations in such transitions often exhibit multiple length and time scales.

Purpose of the Study:

• To investigate the antiferrodistortive displacive transition in SrTiO3.
• To spatially and temporally resolve the different components of critical fluctuations.

Main Methods:

• Coherent X-ray diffraction (CXD) using microbeam techniques.
• Analysis of diffraction patterns to disentangle spatial and temporal dynamics.

Main Results:

• Spatially resolved two distinct components of critical fluctuations: a broad (short-length scale) and a narrow (long-length scale).
• Identified 100-micrometer-scale spatial variations in the narrow component.
• Observed static speckle patterns on a ~10 nanosecond timescale for both components, indicating static ordered domains in the narrow component.
• Interpreted speckles in the broad component as evidence of slow dynamics, akin to a central peak in neutron scattering.

Conclusions:

• The study successfully disentangled spatial and temporal characteristics of critical fluctuations in SrTiO3.
• The findings support the interpretation of the narrow component as static domains and the broad component as slow dynamical processes.
• Coherent X-ray diffraction provides a powerful tool for probing complex phase transitions.