Modeling the conductivity around the dimensionality-controlled metal-insulator transition in LaNiO_3/LaAlO_3 (100) superlattices

摘要

A dimensionality controlled metal insulator transition in epitaxial [LaNiO_3 (d nm)/LaAlO_3(2 nm)]_(10) (100) superlattices (thereafter [d/2]_(10) SLs) is demonstrated for decreasing LaNiO_3 single layer thickness from 4 nm down to 1.2 nm. The [4/2]_(10) SL shows metallic behavior with positive resistivity temperature coefficient, while the [2/2]_(10) SL shows a metal-insulator transition with crossover from 3D to two-dimensional single-layer dimensionality. Strong localization appears for the [1.2/2]_(10) SL with the resistivity being dominated by two-dimensional variable range hopping with a localization length of about 0.035 nm.