Absence of Andreev bound states in b PdBi 2 probed by point contact Andreev reflection spectroscopy
We report point contact spectroscopic studies on high quality single crystalline \ensuremath{\beta}\text{\ensuremath{ \mathrm{PdBi}}_{2} with a superconducting {T}_{c}=5.2\phantom{\rule{0.28em}{0ex}\mathrm{K} Our measurements show a typical double peak structure in the voltage biased junction conductance at low temperatures, probably excluding the existence of topological Andreev bound states. The conductance curves can be well fitted with the standard Blonder Tinkham Klapwijk model for $s$ wave superconductors, yielding a superconducting gap \mathrm{\ensuremath{\Delta}}_{0}\ensuremath{\simeq}0.92\phantom{\rule{0.28em}{0ex}\mathrm{meV} with $2{\mathrm{\ensuremath{\Delta}}_{0}{k}_{B}{T}_{c}\ensuremath{\sim}4.1$ Our results strongly suggest that \ensuremath{\beta}\text{\ensuremath{ \mathrm{PdBi}}_{2} is a conventional intermediate coupling $s$ wave superconductor.