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The diffusivity ratio η, which measures the relative intraband scattering in the π and σ bands in MgB2 has been determined by fitting the Hc2 (T) at T ∼ Tcand by Point Contact Andreev Reflection. We find a satisfactory agreement between the values for η obtained by both methods for c-axis orientated MgB2 thin films. Point contact Andreev Reflection was then applied to bulk MgB2 containing Mg vacancies. Spectra obtained in zero field indicate a distribution of the two gaps Δσ,π but no merging of the values with increased magnesium deficiency. Spectra fitted as a function of field are consistent with an increase in π intraband scattering with increasing magnesium deficiency. Measurement of the point contact Andreev reflection spectra as a function of temperature revealed features not immediately expected from current theoretical models. © 2008 IOP Publishing Ltd.
Yates, K. A., Miyoshi, Y., Grunwell, J., Riggall, K., Bugoslavsky, Y., Chen, S. K., … Cohen, L. F. (2008). Extracting the diffusivity ratio from point contact Andreev reflection spectroscopy and upper critical field measurements in MgB2. Journal of Physics: Conference Series, 97(1). https://doi.org/10.1088/1742-6596/97/1/012213