NMR Under Uniaxial Strain

We have recently developed a new capability to perform NMR on crystals under uniaxial strain.  Several correlated electron systems exhibit nematic phase transitions, in which the electronic degrees of freedom break the underlying symmetry of the crystalline lattice. This phase is usually linearly coupled to the lattice distortion, hence applying strain to a crystal can induce a nematic phase.    Piezoelectric actuators can apply both positive (tensile) as well as negative (compressive) strain, and the displacement can be controlled with precision at the nm level.  The NMR properties can be tuned with this approach. In particular, we have found that the spin-lattice relaxation changes dramatically under strain in the iron pnictide system, BaFe2As2.