Effect of microstructure on the electronic transport properties of epitaxial CaRuO$_3$ thin films

TL;DR

This study investigates how oxygen pressure during growth influences the structural, electronic, and magnetic properties of CaRuO₃ thin films, revealing correlations between growth conditions, surface quality, and transport behavior.

Contribution

It provides a comprehensive analysis of how oxygen partial pressure affects the microstructure and transport properties of epitaxial CaRuO₃ films, highlighting the link between growth conditions and physical characteristics.

Findings

High oxygen pressure yields smoother, metallic films with minimal surface roughness.

Low oxygen pressure results in rougher films exhibiting ferromagnetic signatures.

Resistance noise correlates with defect density and disorder in the films.

Abstract

We have carried out extensive comparative studies of the structural and transport properties of CaRuO$_3$ thin films grown under various oxygen pressure. We find that the preferred orientation and surface roughness of the films are strongly affected by the oxygen partial pressure during growth. This in turn affects the electrical and magnetic properties of the films. Films grown under high oxygen pressure have the least surface roughness and show transport characteristics of a good metal down to the lowest temperature measured. On the other hand, films grown under low oxygen pressures have high degree of surface roughness and show signatures of ferromagnetism. We could verify that the low frequency resistance fluctuations (noise) in these films arise due to thermally activated fluctuations of local defects and that the defect density matches with the level of disorder seen in the films through structural characterizations.