Design of Ferroelectric Valve: A Spin-Valve-Analogous Structure for Modulating Electrical Resistance

The spin valve features a magnetic multilayer structure, wherein the resistance of the intervening non-magnetic layer can be modulated by adjusting the spin orientations of adjacent magnetic layers. While ferroelectricity is often regarded as analogous to ferromagnetism, a device analogous to a spin valve-a ferroelectric valve capable of modulating resistance through alterations in the polarization orientations of neighboring ferroelectric layers-has yet to be realized. This study constructs a ferroelectric valve consisting of a LaTiO_3.5/LaTiO₃/LaTiO_3.5 multilayer structure and demonstrated that the electrical resistance of LaTiO₃ varies with the switching of ferroelectric polarization in adjacent LaTiO_3.5 layers between parallel and antiparallel configurations. Using aberration-corrected transmission electron microscopy combined with first-principles calculations, atomic and electronic structural changes within the ferroelectric valve under parallel and antiparallel polarization configurations are systematically investigated. The findings reveal that when the polarization orientations of adjacent ferroelectric LaTiO_3.5 layers are parallel, the conductive LaTiO₃ layer exhibits a high-resistance state. Conversely, when these polarizations are antiparallel, the LaTiO₃ layer demonstrates a low-resistance state. Notably, this ferroelectric valve displays strong anisotropic conductivity and its preferred conducting direction can be modulated by varying the polarization orientations. Our study establishes the structural and electronic basis for a ferroelectric valve, demonstrating its operational mechanism at the atomic scale. This discovery offers promising prospects for designing next-generation ferroelectric memory components.