Thermodynamics of an incommensurate quantum crystal

الأصل · EN

We present a simple theory of the thermodynamics of an incommensurate quantum solid. The ground state of the solid is assumed to be an incommensurate crystal, with quantum zero-point vacancies and interstitials and thus a non-integer number of atoms per unit cell. We show that the low temperature variation of the net vacancy concentration should be as T⁴, and that the first correction to the specific heat due to this varies as T⁷; these are quite consistent with experiments on solid ⁴He. We also make some observations about the recent experimental reports of ``supersolidity'' in solid ⁴He that motivate a renewed interest in quantum crystals.