Manipulating superconductivity in ruthenates through Fermi surface engineering

The key challenge in superconductivity research is to go beyond the historical mode of discovery-driven research. We put forth a new strategy, which is to combine theoretical developments in the weak-coupling renormalization-group approach with the experimental developments in lattice-strain-driven Fermi surface engineering. For concreteness we theoretically investigate how superconducting tendencies will be affected by strain engineering of ruthenates' Fermi surface. We first demonstrate that our approach qualitatively reproduces recent experiments under uniaxial strain. We then note that the order of a few percent strain, readily accessible to epitaxial thin films, can bring the Fermi surface close to van Hove singularity. Using the experimental observation of the change in the Fermi surface under biaxial epitaxial strain and ab initio calculations, we predict Tc for triplet pairing to be maximized by getting close to the van Hove singularities without tuning on to the singularity.