Strain Control of Fermiology and Many-Body Interactions in Two-Dimensional Ruthenates

TL;DR

This study shows how epitaxial strain can be used to control the Fermi surface topology and many-body interactions in 2D ruthenates, revealing critical fluctuations and mass enhancements near topological transitions.

Contribution

It demonstrates the use of epitaxial strain to manipulate electronic structure and interactions in Sr2RuO4 and Ba2RuO4, advancing control over correlated materials.

Findings

Signatures of critical fluctuations near the topological transition.

Rapid increase in quasiparticle mass with Ru-O bond distance.

Epitaxial strain as a disorder-free method to tune emergent properties.

Abstract

Here we demonstrate how the Fermi surface topology and quantum many-body interactions can be manipulated via epitaxial strain in the spin-triplet superconductor Sr$_2$RuO$_4$ and its isoelectronic counterpart Ba$_2$RuO$_4$ using oxide molecular beam epitaxy (MBE), \emph{in situ} angle-resolved photoemission spectroscopy (ARPES), and transport measurements. Near the topological transition of the $\gamma$ Fermi surface sheet, we observe clear signatures of critical fluctuations, while the quasiparticle mass enhancement is found to increase rapidly and monotonically with increasing Ru-O bond distance. Our work demonstrates the possibilities for using epitaxial strain as a disorder-free means of manipulating emergent properties, many-body interactions, and potentially the superconductivity in correlated materials.