Thermoelectric Polarization Transport in Ferroelectric Ballistic Point Contacts

We formulate a scattering theory of polarization and heat transport through a ballistic ferroelectric point contact. We predict a polarization current under either an electric field or a temperature difference that depends strongly on the direction of the ferroelectric order and can be detected by its magnetic stray field and associated thermovoltage and Peltier effect.

Figure 1

(a) Polarization transport between two ferroelectric reservoirs ($R1$ and $R2$) connected by a ferroelectric lead (left panel). The polarization current induces a magnetic field (right panel). In accordance with the polarization current direction as in (a), there are an electric field applied on the $R1$ along the direction of ferroelectric order and a temperature difference ($\mathrm{\Delta }T>0$) on the $R2$. (b) The ferroelectric lead is divided by the scattering region into two parts of lead 1 and 2 that are in adiabatic contact with the $R1$ and $R2$, respectively.

Figure 2

Diatomic ferroelectric chains with spontaneous polarization (a) perpendicular and (b) parallel to the chain axis, respectively. The polarization conductance ($G$) and Peltier coefficient ($\mathrm{\Pi }$) as a function of temperature for the perpendicular (c) and parallel (d) configurations, where TA and TO in (d) represent the contributions from the transverse acoustic and optical phonons, respectively.