A novel state of matter consisting of condensed fermions has been created by Deborah Jin and colleagues, Cindy Regal and Marcus Greiner, at NIST and the University of Colorado. The team showed that when fermionic potassium-40 atoms are held at microkelvin temperatures they pair up into bosons (rather as electrons form Cooper pairs in the BCS theory of superconductivity or He-3 pairs in superfluidity, but with much stronger binding) and then condense, forming a Bose-Einstein condensate, even though they're really fermions. The strength with which the pairing takes place can be tuned with a magnetic field, which makes this a very interesting experimental system. Even more excitingly, the small ratio between the Fermi and condensation temperatures relative to that observed in normal and even high-Tc superconductors could point the way to room-temperature superconductivity.
Further reading
C A Regal, M Greiner and D S Jin 2004 Phys. Rev. Lett. 92 040403.