An interesting type of superconductors available to us today are the ones that achieve this property at room temperature, with only the small snag that they require crushing pressures that would render biological lifeforms into a very thin layer of molecules. What these however suggest is that something in these materials changes at these high pressures, and if we could retain that state upon releasing said pressure, we might be able to have our superconducting cake and eat it too.
This is effectively what researchers recently achieved, with a research article in PNAS Physics by [Liangzi Deng] et al. covering the pressure-quench protocol (PQP) that they used for this feat. There is also an associated easy-to-read press release by Argonne National Laboratory (ANL) as well as one by the University of Houston.
Target material was a cuprate, specifically HgBa2Ca2Cu3O8+δ, also known as the HBCCO series or Hg1223 for short. Hg1223 has been the subject of much research and experimentation since the 1990s, with it demonstrating a transition temperature (Tc) of 133 K (-140°C). With this quenching method – which sees the high pressures on the cooled sample suddenly released – this bumped the Tc up to 151 K, or -122°C.
While still a far cry from room temperature superconductors, managing to lock in these superconducting properties at an 18 K higher temperature using a straightforward procedure does raise the prospect of massively reducing the cooling needs for superconductors.