Study of large crystallographic strain in rutile-type ruthenium dioxide epitaxial thin film

概要

In this chapter, I introduced the research background. Strain engineering has gained considerable attention for tuning the physical properties of functional oxides. For example, in the case of perovskite oxide with the cubic structures, a wide variety of commercially available single crystal substrates are present, and by choosing such substrates, strain engineering on physical properties has been investigated [1]. Rutile-type RuO2 is a functional transition metal oxide with an exceptional combination of low resistivity and high thermal/chemical stability and leads to practical applications such as electrodes and catalysts [2]. For both these applications, RuO2 is often used in the form of thin films and subjected to lattice strain. Recently, strain engineering on RuO2 leads to the emergence of superconductivity by the application of epitaxial strain [3]. Additionally, the catalytic property is also improved by the application of such strain [4,5]. However, strain in rutile oxides is uncontrollable and limited to a small value due to the lack of commercially available lattice-matched single crystal substrates. Although growth-mode induced strain is an alternative approach to control the strain, its amplitude is limited to 1% [6]. In this study, I developed a route to control the strain in rutile-type RuO2 epitaxial thin film and strain engineering on the functionalities.

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