Strontium Titanate Capping Layers as Kinetic Regulators of Redox Phase Transitions in Oxide Heterostructures
Year: 2026
Type: preprint
Abstract: Oxide capping layers are widely used to protect and stabilize thin-film heterostructures, yet their role in governing phase-transition kinetics remains largely unexplored. Here, we uncover the kinetic function of few-nanometer-thick SrTiO$_3$ (STO) capping layers in controlling oxidation and reduction processes, using real-time in situ optical spectroscopic ellipsometry. We show that oxygen diffusion through the nanoscale capping layer constitutes the rate-limiting step, giving rise to diffusion-controlled phase transitions in the underlying materials. As a result, both capping-layer thickness and oxygen partial pressure provide effective handles to tune phase transition temperatures. Quantitative analysis yields an activation energy of $E_A$ = 0.64 $\pm$0.06 eV for oxygen diffusion through STO, highlighting its suitability for precise control of redox reactions in diverse material systems. These results establish oxide capping layers as active kinetic regulators of redox-driven phase transitions and offer a general framework for engineering redox dynamics in complex oxide heterostructures.
Source: arXiv (Cornell University)
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, Pusan National University, Korea Basic Science Institute, Ministry of Science and ICT, South Korea, Division of Materials Research, Basic Energy Sciences, SLAC National Accelerator Laboratory, Division of Materials Sciences and Engineering
OpenAlex ID: W7223687155