Probing quantum materials with uniaxial stress

Over the past approximately 10 years, it has become routine to use piezoelectric actuators to apply large anisotropic stresses to correlated electron materials. Elastic strains exceeding 1% can often be achieved, which is sufficient to qualitatively alter the magnetic and/or electronic structures of a wide range of correlated electron materials. Experiments fall into two broad groups. In one, explicit use is made of the capacity of anisotropic stress to reduce the point group symmetry of the lattice, for example, from tetragonal to orthorhombic. In the other, anisotropic stress is used as a more general, powerful tuning method that, within the elastic limit of the material under test, does not introduce disorder. In this review, we provide a brief recent history of strain tuning, describe current methodology, provide selected examples of the types of experiment that have been done, and discuss the thermodynamics of uniaxial stress.