IS A NONEQUILIBRIUM SUPERSOLID POSSIBLE IN SOLID HE-4

Theoretical calculations have shown that an equilibrium supersolid sta te is possible in a number of systems. The most studied system is soli d He-4, but experimental searches have failed to find evidence for sup ersolid behavior. However, it is possible to create a non-equilibrium supersolid state through Bose condensation of a non-thermal distributi on of vacancies. In this paper, I discuss the relevant properties of s olid He-4 to determine the feasibility of creating such a state in thi s system. While the relevant vacancy parameters are not known with cer tainty, there is a range of allowed values that would allow the creati on of a non-equilibrium supersolid in He-4. (C) 1998 Elsevier Science B.V. All rights reserved.