Melting without heat?

Why do materials melt? Because they get hot – this normally means that the atoms that make up the material vibrate so energetically that they escape their confined environment and start to move around.

This notion of atoms heating up and vibrating more and more gets confused at very short timescales. Using very short intense laser pulses the interactions holding a material can be changed almost instantly. It can (coherently) change form, or melt, before the atoms that make it up can vibrate even a couple of times.

Simulations from Matt Watkins and collaborators in UCL and Japan show that for Tungsten the occurrence of the solid-solid phase transformation is in competition with ultrafast nonthermally assisted melting with the strength of the electron-phonon coupling determining the lifetime of the new solid phase.

The ability to change material properties essentially instantly would have exciting application in both data storage and engineering applications. The results are published in Physical Review B:

Murphy ST, Daraszewicz SL, Giret Y, Watkins M, Shluger AL, Tanimura K, and Duffy DM “Dynamical simulations of an electronically induced solid-solid phase transformation in tungsten”, Phys. Rev. B 92, (2015) 134110.

medium - Matt


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