  We investigate finite-size effects on the phase structure of chiral and
difermion condensates at finite temperature and density in the framework of the
two-dimensional large-$N$ Nambu-Jona-Lasinio model. We take into account
size-dependent effects by making use of $zeta$-function and compactification
methods. The thermodynamic potential and the gap equations for the chiral and
difermion condensed phases are then derived in the mean-field approximation.
Size-dependent critical lines separating the different phases are obtained
considering anti-periodic boundary conditions for the spatial coordinate.
