%0 Journal Article %K Titanium compounds %K Phase transitions %K Ferroelectricity %K Lead titanate %K Vortex flow %K Degrees of freedom (mechanics) %K High resolution transmission electron microscopy %K Interface states %K Strontium titanates %K Ferroelectric state %K Ferroelectric superlattice %K Long range interactions %K Memory applications %K Number of unit cells %K Phase field models %K Polar structures %K Vortex state %A S.-L Hsu %A M.R McCarter %A C Dai %A Z Hong %A L.-Q Chen %A C.T Nelson %A L.W Martin %A Ramamoorthy Ramesh %B Advanced Materials %D 2019 %G eng %I Wiley-VCH Verlag %R 10.1002/adma.201901014 %T Emergence of the Vortex State in Confined Ferroelectric Heterostructures %V 31