Enhanced magnetic and thermoelectric properties in epitaxial polycrystalline SrRuO3 thin films

• Published in: Nanoscale Vol. 10; no. 9; pp. 4377 - 4384
• Main Authors: Woo, Sungmin, Lee, Sang A, Mun, Hyeona, Choi, Young Gwan, Chan, June Zhung, Shin, Soohyeon, Lacotte, Morgane, Adrian, David, Prellier, Wilfrid, Park, Tuson, Won Nam Kang, Lee, Jong Seok, Kim, Sung Wng, Choi, Woo Seok
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2018
• Subjects: Coalescing; Compressive properties; Crystal structure; Crystallinity; Electron transport; Epitaxy; Ferromagnetic materials; Grain boundaries; Magnetic properties; Magnetism; Polycrystals; Single crystals; Strontium titanates; Substrates; Thermal conductivity; Thermodynamic properties; Thin films; Transition metal oxides
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c7nr09627e

Transition metal oxide thin films show versatile electric, 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 magnetic and thermal transport properties by fabricating single- and polycrystalline epitaxial SrRuO3 thin films using pulsed laser epitaxy. Using the epitaxial stabilization technique with an atomically flat polycrystalline SrTiO3 substrate, an epitaxial polycrystalline SrRuO3 thin film with the crystalline quality of each grain comparable to that of its single-crystalline counterpart is realized. In particular, alleviated compressive strain near the grain boundaries due to coalescence is evidenced structurally, which induced the 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 an enhanced thermoelectric efficiency in the epitaxial polycrystalline thin films, compared with their single-crystalline counterpart.