Published on Wednesday June 22, 2011
An article by Professor James Rondinelli, along with co-author Sinisa Coh of the Department of Physics and Astronomy at Rutgers University, has recently been published in Physical Review Letters (Volume 106, Issue 23).
"Large Isosymmetric Reorientation of Oxygen Octahedra Rotation Axes in Epitaxially Strained Perovskites" details the discovery of a symmetry-preserving (isosymmetric) structural transition hidden in materials with polyhedral frameworks and encourages closer studies of epitaxially grown perovskite oxide films. Rondinelli and Coh report that such a hidden transition occurs between two crystalline phases with corner-connected octahedra (shown in the Figure to the right) grown in thin film form. Remarkably, this first-order transition replicates the phase boundary behavior of the liquid-gas transition found in water. It is also technologically enticing, because most phase change materials, which are used in computer memory (RAM applications) or for long term data storage, lose symmetry upon switching. This makes them prone to fatigue and shortens their operational lifetimes. These new thin film oxides, however, should be less susceptible to cycling-degradation as the symmetry remains intact when switched.
Continued studies of these rare transitions could therefore dramatically redefine integrated material performance in the future.