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September 16, 2009

Berkeley Lab: Putting a Strain on Nanowires Could Yield Colossal Magnetoresistance


These optical images of a multiple-domain vanadium oxide microwire taken at various temperatures show pure insulating (top) and pure metallic (bottom) phases and co-existing metallic/insulating phases (middle) as a result of strain engineering. (Image from Junqiao Wu)

Berkeley Labs found that structural irregularities in correlated electron materials - a phenomenon known as “phase inhomogeneity” – could be engineered at the sub-micron scale to achieve such desired properties as colossal magnetoresistance.

This unique class of materials is commanding much attention now because they can display properties such as colossal magnetoresistance and high-temperature superconductivity, which are highly coveted by the high-tech industry



Wu says that in the future strain engineering might be achieved by interfacing a correlated electron material such as vanadium oxide with a piezoelectric - a non-conducting material that creates a stress or strain in response to an electric field.

“By applying an electric field, the piezoelectric material would strain the correlated electron material to achieve a phase transition that would give us the desired functionality,” says Wu. ”To reach this capability, however, we will first need to design and synthesize such integrated structures with good material quality.”



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