Supersolid Phase in Helium-4

Original · EN

The probable observation of a supersolid helium phase was recently reported by Kim et al. In this article, we confirm their speculation. Based on a theoretical model for solid helium-4, we show that the emergence of such a phase is inevitable. This is the first instance of Bose-Einstein condensation (BEC) in a solid. We calculate the BEC transition temperature (Tc) and the Landau critical velocity (vc) from the model, which respectively are 215 mK and 251 μms⁻¹. They are in excellent agreement with the experimental results; Tc=175 mK and vc ≤ 300 μms⁻¹. We also prove that our model possesses the necessary and sufficient condition for the emergence of supersolidity. We briefly comment about similar behaviour in ³He.