Andreev spectroscopy of CrO2 thin films on TiO2 and Al2O3

• Published in: Europhysics letters Vol. 103; no. 6
• Main Authors: Yates, K. A., Anwar, M. S., Aarts, J., Conde, O., Eschrig, M., Löfwander, T., Cohen, L. F.
• Format: Journal Article
• Language: English
• Published: EDP Sciences, IOP Publishing and Società Italiana di Fisica 01.09.2013
• Subjects: 72.25.Mk; 74.45.+c; 85.75.-d
• ISSN: 0295-5075; 1286-4854; 1286-4854
• DOI: 10.1209/0295-5075/103/67005

Here we analyse the spectroscopic information gathered at a number of single CrO2/Pb interfaces. We examine thin films requiring additional interfacial layers to generate long-range spin triplet proximity effect superconductivity (CrO2/TiO2) or not (CrO2/Al2O3). We analyse the data using two theoretical models and explore the use of a parameter-free method to determine the agreement between the models and experimental observations, showing the necessary temperature range that would be required to make a definitive statement. The use of the excess current as a further tool to distinguish between models is also examined. The analysis of the spectra demonstrates that the temperature dependence of the normalised zero-bias conductance is independent of the substrate onto which the films are grown. This result has important implications for the engineering of interfaces required for the long-range spin triplet proximity effect.