STRAIN EFFECT IN IRON CHALCOGENIDE SUPERCONDUCTORS

In FeSe this interplay leads to a symmetry-broken state (often referred to as nematic state) that is characterized by small orthorhombic distortions of the lattice and a large anisotropy of the electronic properties. Nematicity created a lot of excitement since superconductivity may be boosted by the related fluctuations.

• The first objective is to track down possible signatures of the interrelation of the normal, nematic and superconducting states. To this end, lattice, charge and spin excitations in Fe(Se:S) single crystals will be studied spectroscopically as a function of temperature and doping.
• The second objective is to scrutinize the influence of a symmetry-breaking strain field on the various phase transitions. It is intended to monitor the effects by Raman studies of Fe(Se:S) single crystals.

Based on obtained results, a possibility for engineering strain devices that exploit properties of iron-chalcogenide superconductors will be explored.