The discovery of new high-temperature superconductors1 based on FeAs has led to a new gold rush in high-TC superconductivity. All of the new superconductors share the same common structural motif of FeAs layers and reach TC values up to 55 K (ref.2). Recently, superconductivity has been reported in FeSe (ref.3), which has the same iron pnictide layer structure, but without separating layers. Here, we report the magnetic and electronic phase diagram of Β-Fe1.01 Se as a function of temperature and pressure. The superconducting transition temperature increases from 8.5 to 36.7 K under an applied pressure of 8.9 GPa. It then decreases at higher pressures. A marked change in volume is observed at the same time as TC rises, owing to a collapse of the separation between the Fe 2 Se2 layers. No static magnetic ordering is observed for the whole p-T phase diagram. We also report that at higher pressures (starting around 7 GPa and completed at 38 GPa), Fe1.01 Se transforms to a hexagonal NiAs-type structure and exhibits non-magnetic behaviour.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering