Helium (He4) nanodroplets provide a unique environment to observe the microscopic origins of superfluidity. The search for another superfluid substance has been an ongoing quest in the field of quantum fluids. Nearly two decades ago, experiments on doped parahydrogen (p-H2) clusters embedded in He4 droplets displayed anomalous spectroscopic signatures that were interpreted as a sign of the superfluidity of p-H2 [S. Grebenev et al., Science 289, 1532 (2000)SCIEAS0036-807510.1126/science.289.5484.1532]. Here, we observe, using first-principles quantum Monte Carlo simulations, a phase separation between a symmetric and localized p-H2 core and He4 shells. The p-H2 core has minimal superfluid response. These findings are consistent with the recorded spectra but not with their original interpretation, and lead us to conclude that doped p-H2 clusters form a nonsuperfluid core in He4 droplets.

Physical Review Letters
Department of Chemistry

Li, H. (Hui), Zhang, X.-L. (Xiao-Long), Zeng, T, Le Roy, R.J. (Robert J.), & Roy, P.-N. (Pierre-Nicholas). (2019). Suppression of Parahydrogen Superfluidity in a Doped Nanoscale Bose Fluid Mixture. Physical Review Letters, 123(9). doi:10.1103/PhysRevLett.123.093001