Andreev reflections at metal/superconductor point contacts: Measurement and analysis

Evidence for spin mixing in holmium thin film and crystal samples

“…The results indicate that at low R C in both the crystal and the film spin-mixing occurs. Note that in PCAR can decrease either due to a cleaner interface or due to an increase in the physical size of the contact 30,44 . This may explain why the effects observed here vary in magnitude between different contacts [for example the square and star datasets in Fig.…”

“…3(a) and 3(b) respectively. The P-Z relationship of an S/F interface always takes a similar form in that high P is associated with low Z and vice versa and the origin of this dependence has been widely discussed in the literature [28][29][30][31][32] . The 'intrinsic' polarization is usually obtained by extrapolating a P-Z plot to low Z -although not usually to Z = 0 29 because Z also includes the effect of Fermi velocity mismatch between the S/F materials 33 .…”

Influence of Barrier Width on Spin-Polarisation Measured by Point Contact Andreev Reflection

“…3 for P = 0 and 80% and different barrier widths using the BTK model [7]. In the fitting procedure, we treat P BTK , Z, ω, Δ as free fitting parameters, where Δ is the superconducting energy gap and ω is a broadening parameter [3].…”

“…The fully polarised part is calculated by putting A N (E; d, Z) = 0 in formula (1). In practice, (4) is used to extract the values of spinpolarisation from the measurements of the total conductance by an appropriate fitting procedure [6,7,9,10].…”

“…The interpretation of PCAR experimental data is based on formula derived from the BTK model [5] or its extensions [6,7], modified to include a spin polarisation of the metal [1]. Typically, all these models assume that the ferromagnetsuperconductor (FM/SC) interfaces are described by the Dirac's delta potential with a finite transparency that is related to the microscopic properties in a non-trivial way [3].…”