Many at the EB have wondered about this and there has been no other topic that has been more controversial. Some here have done extensive work with helium-4 or whatever, Doug for sure. DR has been on the trail, so he may not be quite up to speed. I am convinced that Bobal will have some insightful comments.
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“One of the issues has been whether or not a boson system can simultaneously form a superfluid and a crystal at the same place,” Mila says. “Most of the work has been done with helium-4, but at this point it is still debated whether a supersolid phase can be realized. But,” he continues, “for bosons already on a lattice, it may be easier to make a superlattice and realize a supersolid which may be seen in nature.”...
...Mila admits that right now this work is still speculative: “So far compelling evidences have not been detected in the best copper oxide candidate [SrCu2(BO3)2].” Mila points out that, “a supersolid is expected to undergo two phase transitions upon lowering the temperature where the two types of order develop, and only one has been reported in that compound. One cannot exclude that experiments were not performed at low enough temperature, but this could be due as well to anisotropy effects.” (more)
