Mode dependent scattering of phonons by domain walls in ferroelectric KDP

A phononic switch based on ferroelectric domain walls

“…A proof-of-concept of this idea has been experimentally observed in different ferroelectrics and DW configurations. Mante et al 9 first and Weilert et al 10,11 15 To this end, we obtained the atomic force constants from second-principles model potentials 16 and performed harmonic (ballistic) phonon transport simulations within the nonequilibrium Green's functions formalism. The calculations revealed an unprecedented polarization-dependent phonon scattering mechanism occurring at PbTiO 3 180 • DWs capable to longitudinally polarize a thermal flux when piercing several DWs.…”

Effects of coherent ferroelastic domain walls on the thermal conductivity and Kapitza conductance in bismuth ferrite

“…The domain walls in the BiFeO 3 films, which occur on the nanometer scale, cause additional phonon scattering events that will add additional resistances to thermal transport. [12][13][14] The challenge in utilizing BiFeO 3 in future applications, therefore, lies in understanding how phonon transport is affected by domain wall scattering. Although previous work has extensively examined the effects of grain boundaries on phonon transport and thermal conductivity, [15][16][17][18][19][20] these grain boundaries can represent incoherent, highly disordered regions.…”

“…32,33 This idea of thermal boundary conductance across domain walls, or "internal interfaces," was first observed in potassium dihydrogen phosphate (KDP) at liquid helium temperatures where phonon transport in the KDP was mostly ballistic, and phonon transmission across the domain walls was nearly entirely specular and elastic. 12,13 To calculate the thermal boundary conductance of the domain walls in the BiFeO 3 films, we use a series resistor approach utilizing the data presented in Fig. 2.…”

“…It is possible that this phenomenon is intrinsic to ferroelastic domain boundaries as Weilert and coworkers measured substantially lower thermal conductivities in polydomain KDP compared to poled crystals. 12,13 Another possible source of the thermal resistance is the presence of inhomogeneous strain at the domain walls. Interestingly, .…”

Abnormal thermal conductivity of [720]‐oriented BaTiO3 single crystal

“…Generally, the grain boundary has a great impact on phonon transport and thermal conductivity in ferroelectric materials 15–17. Previous studies demonstrated that domain walls could add an additional effect to thermal transport of BiFeO 3 multiferroic thin films 18, 19, which revealed that the thermal conductivity was closely related to domain variants, resulting in a remarkable decrease in thermal conductivity due to more phonons scattered by more domain walls. Thus the domain wall density plays an important role in the thermal transport behavior.…”