Ferroelectric quantum criticality and enhanced superconductivity in plastically deformed strontium titanate
MPSD Seminar
- Date: May 26, 2021
- Time: 04:00 PM - 05:00 PM (Local Time Germany)
- Speaker: Sajna Hameed
- University of Minnesota
- Location: online via Zoom
- Host: Michael Först
The properties of
quantum materials are commonly tuned using experimental variables such as pressure, magnetic field and
doping. Here we explore a different approach: irreversible, plastic deformation of single crystals. We
show for the superconductor SrTiO3
that compressive plastic
deformation induces low-dimensional superconductivity significantly above the superconducting transition temperature (Tc) of undeformed samples, with evidence of
possible superconducting
correlations at temperatures two orders of magnitude above the bulk Tc. The
superconductivity enhancement is correlated with the appearance of
self-organized dislocation structures,
as revealed by diffuse neutron and X-ray scattering. We also observe signatures
of deformation-induced quantum-critical ferroelectric fluctuations and
inhomogeneous ferroelectric order via Raman scattering.
These results suggest that the strain surrounding the self-organized dislocation structures
induces local ferroelectricity and quantum-critical dynamics that strongly influence Tc, consistent with a theory of
superconductivity enhanced by soft polar
fluctuations. More broadly, our results demonstrate the promise of plastic
deformation and dislocation
engineering as tools to manipulate electronic properties of quantum materials
[1].
[1] S. Hameed, D.
Pelc, Z. W. Anderson, A. Klein, R. J. Spieker, L. Yue, B. Das, J. Ramberger, M. Lukas, Y. Liu, M. J. Krogstad, R. Osborn,
Y. Li, C. Leighton, R. M. Fernandes and M. Greven, arXiv:2005.00514 (2020)