Exotic Phase Competition in Ferroic Materials

A team of students and postdocs lead by Prof. Lane Martin and Prof. R. Ramesh in Materials Science and Engineering and in collaboration with researchers from Pennsylvania State University, Argonne National Laboratory, the National Center for Electron Microscopy and the Advanced Light Source at Lawrence Berkeley National Laboratory, the University of Colorado, Boulder, the Universidad del Pais Vasco (Spain), the Universidad de Cantabria (Spain), and the Luxembourg Institute of Science and Technology have made an important observation about the coexistence and electric-field control of ferroelectric and vortex order. Vortices – like those one can observe in fluids, from the swirl of milk in your coffee to the massive storm that ruins your weekend – are fairly common in physics where they occur in superconducting materials exposed to magnetic fields or in Bose–Einstein gases, and are indicative of intriguing dynamics near a phase transition. The work, published in Nature Materials, reveals the coexistence of polarization vortices with other forms of polar ordering in finely-layered perovskite oxides. As noted by Prof. Matthew Dawber of Stoney Brook University, “this is similar to exploring how a river simultaneously has steady flow and whirlpools, and seeing how conditions affect whirlpool size and location. For a river, you cannot arrange different regions in an easily controllable and precise fashion — for polarization vortices, however, Martin and co-workers demonstrate that you can” do this in these samples. This observation has particular promise for exciting new properties that could be used for a range of memory, logic, and other applications. More context for this work is provided in a News and Views summary from Prof. Dawber .