Seminar | September 6 | 2-3 p.m. | 120 Latimer Hall
Complex topological configurations are a fertile playground to explore novel emergent phenomena and exotic phases in condensed-matter physics.
For example, the recent discovery of polarization vortices and the associated complex-phase coexistence and response under applied field in superlattices of (PbTiO3)n/(SrTiO3)n suggests the presence of a complex, multi-dimensional system capable of exotic physical responses.
I will discuss the discovery of polar skyrmions in a lead-titanate layer confined by strontium-titanate layers by atomic-resolution scanning transmission electron microscopy (STEM). Phase-field modeling and second-principles calculations reveal that the polar skyrmions have a skyrmion number of +1 and resonant soft X-ray diffraction experiments show circular dichroism confirming chirality.
Such nanometer-scale polar skyrmions are a new state of matter and electric analogs of magnetic skyrmions, and may be envisaged for potential applications in information technologies. I will attempt to describe the exciting observations we have made through these collaborations.
R. Ramesh did his PhD here at UC Berkeley (Go Bears!) in 1987. After award-winning research at Bellcore and a distinguished professorship at Univ of Maryland, he joined the faculty of MSE and Physics in 2004, and is also assoc director of the Energy Technologies lab at LBNL.