Throwing light on nanomaterials

An international team of scientists has used a novel technique to measure, for the first time, the precise conditions at which certain ultrathin materials spontaneously become electrically polarised. The research provides the fundamental scientific basis for understanding this ‘ferroelectric’ state in materials needed for next-generation ‘smart card’ memory chips and other devices.

‘We provide a complete picture of how the ferroelectric transition temperature changes when the electrical and mechanical conditions change within nanoscale ferroelectric materials,’ said Xiaoxing Xi, professor of physics and materials science and engineering at Penn State University, who led the research effort.

The team is the first to use a technique known as ultraviolet Raman spectroscopy to reveal a range of temperatures, thicknesses and structural configurations at which nanoscale barium titanate can store a switchable electric field. The scientists also performed theoretical calculations to predict the point at which materials transition into this ferroelectric state. The results of these calculations closely match the results of the team's experiments.