Superconductivity and Strain Effects in Quantum Paraelectric STO*

We will present our results on investigation of the origin of superconductivity in doped STO using a combination of density functional and strong coupling theories[1]. Our approach suggests a model in which the ferroelectric soft mode fluctuations provide the pairing interaction for superconducting carriers. Based on this model, we made a prediction that superconducting Tc will increase with increasing 18O isotope substitution, a scenario that is experimentally verifiable. We now discuss a proposal to use strain as another tool to control the paraelectric fluctuations and thus control superconductivity in STO[2].

[1]J. Edge et al Phys. Rev. Lett. 115, 247002 (2015),
[2] K. Dunnett, et.al, in preparation,