Nonvolatile and Reversible Ferroelectric Control of Electronic Properties of Bi₂Te₃ Topological Insulator Thin Films Grown on Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ Single Crystals

Abstract

Single-phase (00 l)-oriented Bi₂Te₃ topological insulator thin films have been deposited on (111)-oriented ferroelectric 0.71Pb(Mg_1/3Nb_2/3)O₃-0.29PbTiO₃ (PMN-PT) single-crystal substrates. Taking advantage of the nonvolatile polarization charges induced by the polarization direction switching of PMN-PT substrates at room temperature, the carrier density, Fermi level, magnetoconductance, conductance channel, phase coherence length, and quantum corrections to the conductance can be in situ modulated in a reversible and nonvolatile manner. Specifically, upon the polarization switching from the positively poled P_r⁺ state (i.e., polarization direction points to the film) to the negatively poled P_r^- (i.e., polarization direction points to the bottom electrode) state, both the electron carrier density and the Fermi wave vector decrease significantly, reflecting a shift of the Fermi level toward the Dirac point. The polarization switching from P_r⁺ to P_r^- also results in significant increase of the conductance channel α from -0.15 to -0.3 and a decrease of the phase coherence length from 200 to 80 nm at T = 2 K as well as a reduction of the electron-electron interaction. All these results demonstrate that electric-voltage control of physical properties using PMN-PT as both substrates and gating materials provides a simple and a straightforward approach to realize reversible and nonvolatile tuning of electronic properties of topological thin films and may be further extended to study carrier density-related quantum transport properties of other quantum matter.