Enhanced superconductivity and ferroelectric quantum criticality in plastically deformed strontium titanate

Plastic deformation is shown to tune the quantum degrees of freedom in SrTiO3. The properties of quantum materials are commonly tuned using experimental variables such as pressure, magnetic field and doping. Here we explore a different approach using irreversible, plastic deformation of single crystals. We show that compressive plastic deformation induces low-dimensional superconductivity well above the superconducting transition temperature (T-c) of undeformed SrTiO3, with evidence of possible superconducting correlations at temperatures two orders of magnitude above the bulk T-c. The enhanced superconductivity is correlated with the appearance of self-organized dislocation structures, as revealed by diffuse neutron and X-ray scattering. We also observe deformation-induced signatures of quantum-critical ferroelectric fluctuations and inhomogeneous ferroelectric order using Raman scattering. Our results suggest that strain surrounding the self-organized dislocation structures induces local ferroelectricity and quantum-critical dynamics that strongly influence T-c, consistent with a theory of superconductivity enhanced by soft polar fluctuations. Our results demonstrate the potential of plastic deformation and dislocation engineering for the manipulation of electronic properties of quantum materials.

Automated summary

Plastic deformation has been shown to tune the quantum degrees of freedom in SrTiO3, leading to enhanced superconductivity and the appearance of self-organized dislocation structures. The study also reveals deformation-induced signatures of quantum-critical ferroelectric fluctuations and inhomogeneous ferroelectric order. The results demonstrate the potential of plastic deformation and dislocation engineering for manipulating the electronic properties of quantum materials.