Nanocluster magnetic gel in superfluid He-II

The first results of the study of the structure of an impurity oxygen gel in superfluid He-II and in normal liquid helium have been obtained by the small-angle neutron scattering (SANS) method with cold neutrons. The angular dependence of the neutron scattering intensity $I(q)$ indicates that the characteristic sizes of nanocluster aggregates forming a dispersive system (backbone) of an oxygen gel sample are distributed from $1$ to ${\sim}\,100$ nm. According to the estimates made, if the working cell with superfluid helium cooled below $1.8$ K is placed in a magnetic field of $H\geq 200$ G, the magnetic structure of the nanocluster sample of oxygen gel, which is formed at the condensation of the flow of gaseous $^4$He with the impurity of O$_2$ vapor on the surface of He-II, will be close to ferromagnetic.