Electron-phonon coupling in metallic and plastically deformed strontium titanate*

A significant enhancement of the bulk superconducting transition temperature was recently discovered in electron-doped SrTiO₃ single crystals subjected to plastic deformation [1]. Here we present the results of a titanium L-edge resonant inelastic x-ray scattering study of plastically deformed and undeformed electron-doped SrTiO₃. No change in electronic coupling to longitudinal optical (LO) phonon modes is observed between deformed and undeformed samples, which places new constraints on the nature of the previously observed T_c enhancement. Furthermore, our measurements of samples with different charge-carrier concentrations enable us to obtain new insight into the role of electronic coupling to LO phonon modes in the superconducting pairing mechanism of electron-doped SrTiO₃.

[1] S. Hameed et al., Nat. Mater. 21, 54 (2022)