Electronic specific heat at the boundary region of the metal-insulator transition in the two-dimensional electronic system of κ-(BEDT-TTF)2Cu[N(CN)2]Br

The electronic specific heat of partially deuterated organic conductors kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Br, [where BEDT-TTF denotes bis(ethylenedithio)tetrathiafulvalene], which are situated around the critical boundary of a metal-insulator transition in two dimensions, are studied. It was found that when the system has access to the M-I boundary with the progressive deuteration of BEDT-TTF molecules, the normal-state gamma term diminishes. The absence of mass enhancement is marked as a basis for the future study of electronic features related to the nature of superconductivity and also on the universality and variation of a possible Mott transition in two-dimensional systems.