Coherent growth of oxide films on cleaved layered metal oxide substrate*

Understanding interface-induced effects requires controlled epitaxial growth of thin films on atomically smooth substrate surfaces. While conventional thin film growth on commercial substrates has proven to be a successful route, the appropriate substrate choices are limited and not all of them have well-defined surfaces for the epitaxy. Here we present an alternative method of growing oxide thin films on single-crystal substrates which will greatly increase the availability of substrates for future oxide films growth. La_0.67Sr_0.33MnO₃ thin films were deposited on a cleaved Sr₂RuO₄ single crystal as a prototype system. Cleaving Sr₂RuO₄ in ultra-high vacuum along the [001] direction exposes clean atomically flat, SrO layer terminated surface that extends up to a few micrometers. The surface of the substrate has (√2×√2)R45° reconstruction, but the film maintains (1×1) structure, as determined by the low energy electron diffraction. Atomically sharp interface was probed by scanning tunneling electron microscopy. The surface chemical composition and the film stoichiometry were confirmed by angle-dependent X-ray photoelectron spectroscopy. These systems can serve as a tool to explore proximity effects between superconductors and ferromagnets.