Fig. 4: Derivation of the critical fields from field-dependent resistance measurements.
From: Multiphase superconductivity at the interface between ultrathin FeTe islands and Bi2Te3
a, d show minor (blue arrows) major (ΔR) steps in the zero-field resistance of Si-capped FeTe/Bi2Fe3 for 1 ML and 2 ML FeTe coverages. Respective magnetic field-dependent data is shown in b, e. For reasons of clarity, the data are not shown for all fields measured. Panels c and f plot temperature-dependent critical magnetic fields Bc determined from data b, e at different percentage levels of the total drop ΔR. 25%, 50%, and 75% levels are shown as horizontal lines for clarity. Dotted lines fit the linear temperature-dependence characteristic for orbital pair breaking. The black solid lines represent fits according to Werthamer-Helfand-Hohenberg’s (WHH) theory with values Bc (0) = 260 mT and 1600 mT for 1 ML and 2 ML, respectively. Arrows in c are guides to the eye indicating a change towards high critical fields above the blue-coloured B = 60 mT line.
