A phononic switch based on ferroelectric domain walls

Abstract

The ease with which domain walls (DWs) in ferroelectric materials can be written and erased provides a versatile way to dynamically modulate heat fluxes. In this work we evaluate the thermal boundary resistance (TBR) of 180$^{\circ}$ DWs in prototype ferroelectric perovskite PbTiO$_3$ within the numerical formalisms of nonequilibrium molecular dynamics and nonequilibrium Green's functions. An excellent agreement is obtained for the TBR of an isolated DW derived from both approaches, which reveals the harmonic character of the phonon-DW scattering mechanism. The thermal resistance of the ferroelectric material is shown to increase up to around 20%, in the system sizes here considered, due to the presence of a single DW, and larger resistances can be attained by incorporation of more DWs along the path of thermal flux. These results, obtained at device operation temperatures, prove the viability of an electrically actuated phononic switch based on ferroelectric DWs

Theoretical investigation of lattice thermal conductivity and electrophononic effects in SrTiO3

“…The quadratic dependence of κ on the electric field allows rationalizing the results reported in Fig. 3, where the relative variation of the thermal conductivity of PTO in response to an antiparallel and perpendicular field [11,17] is also reported for comparison. The electrophononic response of PTO for this kind of applied field is linear because of the symmetry breaking associated with the ferroelectric distortion in that material and the reduction of κ in the limit of low fields is larger than the one in STO [17].…”

“…This approach provides a simple and flexible way to dynamically tune the thermal conductivity of a material, but it is subordinated to the availability of materials with large dielectric responses, i.e., materials where an applied electric field results in a significant distortion of the lattice and the heat carrying phonons are affected in a considerable way. In a previous paper we demonstrated such an electrophononic effect in PbTiO 3 (PTO), a ferroelectric oxide where a suitably oriented electric field was shown to be capable of hardening or softening the modes throughout the spectrum or, most * ptorres@icmab.es interestingly for transport-control purposes, to activate different phonon-phonon scattering processes that would be otherwise forbidden by symmetry [11], thus leading to a modulation of the thermal conductivity.…”

Infrared nano-spectroscopy of ferroelastic domain walls in hybrid improper ferroelectric Ca3Ti2O7

“…At the same time, it provides crucial information for the development of ultra low-power devices, switches, polarizers, and computing architectures based upon domain walls [35,36]. Loss mechanisms involving phonons are also key to controlling decoherence in domain wall-based computing architectures [28,37].…”

Ferroelectric Domain Walls in PbTiO3 Are Effective Regulators of Heat Flow at Room Temperature

“…In this regard, ferroelectric DWs can be as effective as multilayer interfaces and grain boundaries in inhibiting the transmission of phonons [5][6][7] , but with the added advantage of being reconfigurable. Recent phonon-transport calculations in multidomain PbTiO3 predict a strong suppression in the transmission of transverse phonons across DWs, leading to a »30-50% calculated decrease of k 8,9 . A reduction of k with the density of DWs has been experimentally observed at low temperatures in bulk single crystals of BaTiO3, KH2PO4 and LiF [5][6][7] and more recently at room temperature in multiferroic BiFeO3 by Hopkins et al, 10 although these results were challenged by Ning et al 11 In addition, the experiments performed by Mante and Volger 5 proved that a large increase in k can be achieved by the application of an electric field, which reduces the DW density, yet the effect is only significant at temperatures below 30 K. Ihlefeld et al 12 achieved »11-13% electric-fieldinduced reduction of k at room temperature in polycrystalline Pb(Zr0.3Ti0.7)O3 films.…”

“…The strong reduction of k observed suggests that DWs are very effective phonon-scatterers, probably over a wide range of wavelengths. 9 Boundary scattering due to film thickness is not critical because the thermal conductivity accumulation function shows that »70% of the room temperature k of PbTiO3 comes from phonons having a mean free path less than 10 nm (see also discussion in the Supp. Info.).…”