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 BiFeO3 (BFO) crystal and multidomain epitaxially grown thin film (similar to 180 nm) on DyScO3 (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.