  The discovery of two-dimensional electron gases (2DEGs) in SrTiO3-based
heterostructures provides new opportunities for nanoelectronics. Herein, we
create a new type of oxide 2DEG by the epitaxial-strain-induced polarization at
an otherwise nonpolar perovskite-type interface of CaZrO3/SrTiO3. Remarkably,
this heterointerface is atomically sharp, and exhibits a high electron mobility
exceeding 60,000 cm2V-1s-1 at low temperatures. The 2DEG carrier density
exhibits a critical dependence on the film thickness, in good agreement with
the polarization induced 2DEG scheme.
