Design strategy for ferroelectric-based polar metals with dimensionality-tunable electronic states

摘要： Since LiOsO3 was discovered, obtaining easy-accessible polar metals for research and applications has been challenging. In this paper, we present a multilayer design strategy, which is configured as ferroelectric layer/carrier reservoir layer/isolation layer/substrate, for obtaining polar metals by electrostatically doping a strained ferroelectric material in a more effective way. In the proposed configuration, both 1 unit-cell thick BaTiO3 and PbTiO3 exhibited considerable Ti off-centering with various strains, which should extend the applicability of ferroelectric-based polar metals in ultra-thin devices. Moreover, engineered by the compressive strain and the BaTiO3 thickness, the design strategy effectively achieved polar metallicity and dimensionality-tunable electronic states associated with the modulation of highly anisotropic properties such as electrical and electronic thermal conductivity, which may be helpful for designing ultra-thin, ultrafast, and low-power switch devices.