Strain fields from coherent domain walls in bismuth ferrite scatter phonons like grain boundaries

Our paper examining the effects of coherent domain walls on the thermal conductivity of bismuth ferrite (BiFeO3) was published in Applied Physics Letters (Appl. Phys. Lett. 102, 121903 (2013)). We show that coherent domain walls can scatter phonons as effectively as incoherent grain boundaries, opening up a new regime of strain engineering of phonon transport.

Abstract

Ferroelectric and ferroelastic domain structure has a profound effect on the piezoelectric, ferroelectric, and dielectric responses of ferroelectric materials. However, domain walls and strain field effects on thermal properties are unknown. We measured the thermal conductance from 100–400K of epitaxially grown BiFeO3 thin films with different domain variants, each separated primarily by 71 deg. domain walls. We determined the Kapitza conductance across the domain walls, which is driven by the strain field induced by the domain variants. This domain wall Kapitza conductance is lower than the Kapitza conductance associated with grain boundaries in all previously measured materials.

This work was partially funded  from the AFOSR Young Investigator Program (FA9550-13-1-0067).