Classifying superconductivity in an infinite-layer nickelate Nd$_{0.8}$Sr$_{0.2}$NiO$_2$
Recently Li et al (2019 Nature 572 624) discovered a new type of oxide superconductor Nd0.8Sr0.2NiO2 with T$_c$ = 14 K. To classify superconductivity in this infinite-layer nickelate experimental upper critical field, B$_{c2}$(T), and the self-field critical current densities, J$_c$(sf,T), reported by Li et al (2019 Nature 572 624), are analysed in assumption of s-, d-, and p-wave pairing symmetries and single- and multiple-band superconductivity. Based on deduced the ground-state superconducting energy gap, $\Delta$(0), the London penetration depth, $\lambda$(0), the relative jump in electronic specific heat at Tc, $\Delta$C/C, and the ratio of 2$\Delta$(0)/k$_B$T$_c$, we conclude that Nd0.8Sr0.2NiO2 is type-II high-$\kappa$ weak-coupled single-band s-wave superconductor.