Anisotropic nonlinear transport in two-dimensional ferroelectrics

TL;DR

This paper investigates how in-plane polarization and magnetic fields influence the anisotropic nonlinear charge transport in 2D ferroelectrics, revealing potential for polarization detection and device design.

Contribution

It provides a theoretical and computational analysis of polarization and magnetic field effects on nonlinear conductivity in 2D ferroelectrics, including analytical formulas and DFT calculations.

Findings

Nonlinear conductivity can be tuned by polarization and magnetic field.

Strong spatial anisotropy in nonlinear conductivity.

Polarity of nonlinear response is locked to polarization direction.

Abstract

The longitudinal nonlinear response plays a crucial role in the nonreciprocal charge transport and may provide a simple electrical means to probe the spin-orbit coupling, magnetic order and polarization states, etc. Here, we report on a study on the polarization and magnetic field control of longitudinal nonlinear transport in two-dimensional (2D) ferroelectrics with in-plane polarization. Based on the Boltzmann transport theory, we first study that using a general Hamiltonian model and show that the nonlinear conductivity can be significantly tuned by the polarization and magnetic field. In addition, the nonlinear conductivity reveals a strong spatial anisotropy. We further derive the analytical formulas for the anisotropic nonlinear conductivity in exact accordance with numerical results. Then, we exemplify those phenomena in the 2D ferroelectric SnTe monolayer in the presence of an external magnetic field based on the density functional theory calculations. It is also revealed that the polarity of nonlinear conductivity is locked to the direction of the polarization, thus pointing to the possibility of the nonlinear detection of polarization states. Our work uncovers intriguing features of the longitudinal nonlinear transport in 2D ferroelectrics and provides guidelines for designing the polarization control of rectifying devices.