Two-fluid-model analysis of low-temperature thermodynamic data for Si : P

A derailed analysis of available low-temperature (T less than or equal to 1 K) thermodynamic response-Function data for Si:P in the vicinity of the me tal-insulator transition has been carried out using a two-fluid model which allows for both localized and itinerant electron contributions. This analy sis provides information on the relative concentration of the two electron "fluids" as a function of the concentration through the critical region. Th e specific-heat data, in both zero and nonzero magnetic fields, is successf ully described in terms of this two-fluid model. [S0163-1829(98)00724-3].