Enhanced magnetic and thermoelectric properties in epitaxial polycrystalline SrRuO3 thin film

TL;DR

This study demonstrates that epitaxial polycrystalline SrRuO3 thin films exhibit enhanced magnetic and thermoelectric properties due to grain boundary effects, achieved through pulsed laser epitaxy on atomically flat substrates.

Contribution

It introduces a method to fabricate high-quality epitaxial polycrystalline SrRuO3 films with improved magnetic and thermoelectric properties, maintaining crystalline quality comparable to single crystals.

Findings

Enhanced ferromagnetic ordering in polycrystalline films

Reduced thermal conductivity due to grain boundary structural variations

Improved thermoelectric efficiency over single-crystalline films

Abstract

Transition metal oxide thin films show versatile electrical, magnetic, and thermal properties which can be tailored by deliberately introducing macroscopic grain boundaries via polycrystalline solids. In this study, we focus on the modification of the magnetic and thermal transport properties by fabricating single- and polycrystalline epitaxial SrRuO3 thin films using pulsed laser epitaxy. Using epitaxial stabilization technique with atomically flat polycrystalline SrTiO3 substrate, epitaxial polycrystalline SrRuO3 thin film with crystalline quality of each grain comparable to that of single-crystalline counterpart is realized. In particular, alleviated compressive strain near the grain boundaries due to coalescence is evidenced structurally, which induced enhancement of ferromagnetic ordering of the polycrystalline epitaxial thin film. The structural variations associated with the grain boundaries further reduce the thermal conductivity without deteriorating the electronic transport, and lead to enhanced thermoelectric efficiency in the epitaxial polycrystalline thin films, compared with their single-crystalline counterpart.