Joerg SCHMALIAN
Manipulating quantum materials via varying external strain has become a powerful tool to manipulate and probe systems as diverse as iron-based superconductors, cuprates, strontium ruthenate, and organic charge transfer salts. Particularly interesting behaviour occurs as strain is used to tune through a phase transition or a critical point. In this talk I will give an overview of the various regimes of strain tuning with systems where strain couples directly to the order parameter or rather to the energy density at the transition. Examples of the former include Mott critical points and nematic transitions, while the latter occurs at certain magnetic or Lifshitz transitions. We discuss phenomena like strain-induced elastic interactions and a new, generalised quantum Harris criterion where strain coupling changes the universality class of a quantum phase transition.