Glassy behavior and dynamic tweed in defect-free multiferroics

XF Wang and EKH Salje and J Sun and XD Ding, APPLIED PHYSICS LETTERS, 112, 012901 (2018).

DOI: 10.1063/1.5006034

Multiferroics often show significant elastic fluctuations even when the transition is strongly stepwise. Molecular dynamics simulations of a generic toy model show the appearance of tweed nanostructures (cross hatched patterns) in the paraelastic phase just above the transition point. This tweed lowers the elastic modulus C-12 when approaching the transition temperature. The spatial and temporal correlations of the tweed structure follow the Vogel-Fulcher relationship, and the Vogel- Fulcher temperature is slightly below the transition temperature T-trans, preventing this glassy state to freeze completely. Spatial correlations of shear strain show that the size of tweed patches reaches about eight lattice spacings near T-trans. Cross- and rod-shaped diffuse scattering, similar to that in relaxors, emerges around hh0* and h00* Bragg reflections. The viscosity of the sample increases dramatically at the transition point with a significant precursor increase in the tweed regime. Published by AIP Publishing.

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