You’d think superconductivity would be easy to detect; it comes with zero electrical resistance, so if you measure resistance, and it’s zero, you’re done. Unfortunately there are many ways to get fooled.
Generally you’ll see multiple pieces of evidence for superconductivity in a new report: Meissner effect, AC susceptibility, temperature-dependent critical field and critical current, single-particle tunneling gap, jump in specific heat at T_c, Josephson tunnelling, AC Josephson effect, etc. (Probably not all of these in one paper, but usually at least a couple in addition to zero resistance.
There is a steady trickle of difficult-to-explain results that look a lot like superconductivity, sometimes at unexpectedly high temperatures. “Tantalizing” is often used.
To read more, click here.