Connection of two classes of unconventional superconductors

Understanding unconventional superconductivity is one of the most challenging and fascinating tasks in solid state physics. Several classes of unconventional superconductors share that superconductivity emerges near a magnetic phase despite the different underlying physics. Two of these unconventional materials are heavy fermion and iron-based superconductors.

The researcher at the Max Planck Institute for Chemical Physics of Solids applied large hydrostatic pressures to small single crystals of CeFeAsO, an iron-based superconducting non-superconducting parent compound, using diamond anvil pressure cells. Using electrical, magnetic and structural measurements they have shown that as the applied pressure increases, the characteristics of the material change from those of a ferrous material to those of a heavy fermion metal.

Surprisingly, a narrow superconducting phase emerges in the border region between the typical spin-density wave magnetism of iron spin-pnictide and a Ce-based Kondo regime. This suggests that the two main phenomena characterizing iron pnictides and the heavy fermions, spin density wave magnetism and the Kondo effect, work together to produce superconductivity in CeFeAsO.

This work is published in Physical Review Letters and was selected by the editors as a suggestion from the PRL editors.