Probing the local thermal conductivity of single- and multidomain ferroelastic variants of BiFeO3 by Raman thermometry

In this work, the optothermal Raman technique was used to measure the local thermal conductivity of macro/single ferroelastic domains of bulk ${\mathrm{BiFeO}}_{3}$ (BFO) crystal and multidomain epitaxially grown thin film (\ensuremath{\sim}180 nm) on $\mathrm{DySc}{\mathrm{O}}_{3}$ (DSO) substrate. Domain walls (DWs) were found to act as effective phonon scatterers, reducing the thermal conductivity at room temperature from 2.17 to 1.16 W/mK and from 9.89 to 3.20 W/mK at 150 K. The results indicate that BFO is a promising candidate for bidirectional thermal conductivity tuning and switchable nonlinear thermal components if the DW density can be modulated by an externally applied field.