Disordered Movement of Atoms Observed in Vanadium Dioxide

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Researchers from Duke University observed chaotic movement of atoms in vanadium dioxide as the material alters the state from insulator to conductor

A team of researchers from Duke University observed a detailed view of vanadium dioxide atom’s movement when an ultrafast laser pulse transforms the material from an electrical insulator to a conductor. The detailed analysis revealed that the atoms shift around in a disordered manner instead of switching from one crystal formation to another in a direct, synchronized manner. According to the researchers, such new insight of the inner workings of vanadium dioxide can facilitate the use of dual nature of the compound. The research was published in the journal Science on November 02, 2018.

The dual nature of vanadium dioxide enables insulator-to-metal transition that takes place when the material is heated above 67 degree Celsius or is beamed with an ultrafast laser pulse. However, the transition takes place within a timescale of around 150 femtoseconds. Mariano Trigo, a physicist at SLAC National Accelerator Laboratory along with the colleagues observed vanadium dioxide using ultra-short pulses of X-ray radiation. The sample was beamed with a superfast laser light that triggered the compound’s insulator-to-metal transition. The compound was later subjected to a series of X-ray pulses measuring a few tens of femtoseconds each.

According to Olivier Delaire, a materials scientist at Duke University and co-author of the study, X-ray radiation scattered off atoms in the material and showed positions of the particles at the time of each pulse. The rapid and intense pulses tracked atoms’ movements with precision and at shorter time intervals compared to other experiments. The atomic snapshots detailed the vanadium atoms’ disorganized movement from one crystal structure to the next. The team performed supercomputer simulations of vanadium atoms in random motion, which matched X-ray scattering patterns from the experiment. According to the researchers, ultrafast insulator-to-metal transition of vanadium dioxide is expected to find application in fast electronic components. Moreover, vanadium dioxide’s rare correlation with light and electricity can be used in devices for camouflage.

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