Competition between Thermal Fluctuations and Disorder in the Crystallization ofHe4in Aerogel

What is it about?

We studied crystallization of superfluid 4He in silica-aerogels to see the effect of disorder on dynamics of the first order phase transition at very low temperatures. In the low temperature limit, thermal fluctuation ceases and novel quantum phenomena are expected to emerge in the dynamics of the quantum matter. By using a variable-volume cell, 4He crystals surrounding the aerogel was mechanically compressed to induce crystallization in the aerogel by keeping a constant temperature. The way of the crystallization of 4He in aerogels showed a dynamical transition due to the competition between thermal fluctuation and disorder: crystals grew via creep at high temperatures and via avalanche at low temperatures.

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