Reversible and nonvolatile manipulation of the electronic transport properties of topological insulators by ferroelectric polarization switching

Reversible and nonvolatile electric-field control of the physical properties of topological insulators is essential for fundamental research and development of practical electronic devices. Here, we report the integration of topological insulator films with ferroelectric Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PMN-PT) single crystals in the form of ferroelectric field-effect devices that allow us to tune the electronic properties of topological insulator films in a reversible and nonvolatile manner. Specifically, gating of Cr-doped Bi 2 Se 3 films with the PMN-PT layer is shown to provide a means to reversibly tune and modulate the carrier density and carrier type, as well as its other properties, such as the conductance, magnetoconductance, Fermi level, phase coherence length, and screening factor of electron–electron interaction by polarization switching at room temperature. These findings provide a simple and direct approach for probing the quantum transport properties of topological insulator films through ferroelectric gating by using PMN-PT. The combination of topological insulators with both ferroelectrically and piezoelectrically active PMN-PT thus offers a promising step toward exploring topological insulator/ferroelectric(piezoelectric) hybrid devices that could utilize not only the ferroelectric field-effect of topological insulator/PMN-PT structures but also the unique properties of respective materials. Topological insulators: Control by ferroelectric switching Electric gating can tune the properties of topological insulators, modifying the carriers’ density and type and Fermi level. Several gating materials can be used, but finding materials that allow the manipulation of these properties in a reversible and nonvolatile way at room temperature while being compatible with solid-state electronics is difficult. Now, an international team of researchers led by Ren-Kui Zheng, Yu Wang and Yu-Kuai Liu demonstrated the ferroelectric gating of the topological insulator Bi 2 Se 3 doped with Cr, using single crystals of the perovskite material Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 . They fabricated field-effect transistors in which they achieved electric-field control of the carrier density and type and of the Fermi level of the topological insulator through polarization switching of the ferroelectric layer. These results represent a step forward in the development of practical electronic devices based on topological insulators.