The electronic screening length, the distance over which an electric field is attenuated in a material, imposes a lower physical bound on the lateral size scaling of semiconductor field effect devices. Alternatives will be needed to achieve devices whose characteristic dimensions approach a nanometer. In this work, we demonstrate the atomic-scale nature of screening at high electron densities, using the polarization field of a ferroelectric oxide, , to electrostatically modulate the metallicity of ultrathin manganite (LSMO) films near the metal-insulator transition. Within the screening length, the transport characteristics of LSMO vary sharply at the scale of a single atomic layer.
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For these experiments, we use with .
Small-angle x-ray reflectivity measurements also reveal a uniform film thickness with a roughness of over a scale, the same as is observed on the substrates.
For these experiments, we use with .
The magnetoresistance ratio (MRR) is defined as . For both heterostructures, the maximum MRR at is , occurring at .
