  The ground-state properties of a few spin-1/2 fermions with different masses
and interacting via short-range contact forces are studied within an exact
diagonalization approach. It is shown that, depending on the shape of the
external confinement, different scenarios of the spatial separation between
components manifested by specific shapes of the density profiles can be
obtained in the strong interaction limit. We find that the ground-state of the
system undergoes a specific transition between orderings when the confinement
is changed adiabatically from a uniform box to a harmonic oscillator shape. We
study the properties of this transition in the framework of the finite-size
scaling method adopted to few-body systems.
