Effects of nematic fluctuations on the elastic properties of iron arsenide superconductors

Phys Rev Lett. 2010 Oct 8;105(15):157003. doi: 10.1103/PhysRevLett.105.157003. Epub 2010 Oct 4.


We demonstrate that the changes in the elastic properties of the FeAs systems, as seen in our resonant ultrasound spectroscopy data, can be naturally understood in terms of fluctuations of emerging nematic degrees of freedom. Both the softening of the lattice in the normal, tetragonal phase as well as its hardening in the superconducting phase are consistently described by our model. Our results confirm the view that structural order is induced by magnetic fluctuations.