A single layer film of an Iron superconductor has a critical temperature above liquid nitrogen. Liquid nitrogen cooled superconductors are far cheaper to operate than those that require lower temperatures.
Recent experiments on FeSe films grown on SrTiO3 (STO) suggest that interface effects can be used as a means to reach superconducting critical temperatures (Tc) of up to 80 K. This is nearly ten times the Tc of bulk FeSe and higher than the record value of 56 K for known bulk Fe-based superconductors.