Impurity-stabilized solid ⁴He below the solidification pressure of pure helium

Moroshkin, Peter; Hofer, Adrian; Ulzega, Simone; Weis, Antoine

doi:10.1038/nphys727

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Journal article

Impurity-stabilized solid ⁴He below the solidification pressure of pure helium

Moroshkin, Peter Department of Physics, University of Fribourg, Switzerland
Hofer, Adrian Department of Physics, University of Fribourg, Switzerland
Ulzega, Simone Department of Physics, University of Fribourg, Switzerland - Laboratoire de résonance magnétique biomoléculaire, EPFL, Lausanne, Switzerland
Weis, Antoine Department of Physics, University of Fribourg, Switzerland

23.09.2007

Published in:

Nature Physics. - 2007, vol. 3, no. <, p. 786 - 789

English The modification of melting temperatures and pressures by dissolved impurities is well known in classical fluids. However, to our knowledge such effects have never been studied in quantum solids because of the difficulties in introducing impurities into such crystals that exist only at cryogenic temperatures, and, in the case of ⁴He, at pressures exceeding 25 bar. Here, we present an effect that occurs during the melting of solid ⁴He doped with nanoscopic impurities (alkali atoms, clusters, ions and electrons): the doped part of the crystal remains solid under conditions at which pure helium is liquid. Using interferometry, we found that the density of the solid structure lies between the densities of pure liquid and pure solid helium. We tentatively interpret the solid structure as being an aggregation of positively charged particles and electron bubbles.

Faculty

Faculté des sciences et de médecine

Department

Département de Physique

Language