Cold Fermionic Atoms in Two Dimensional Traps--Pairing versus Hund's Rule

The microscopic properties of a finite many-body system of few interacting cold fermionic atoms confined in a two-dimensional (2D) harmonic trap are studied by numerical diagonalization. For repulsive interactions, a strong shell structure dominates with Hund's Rule acting in its extreme for mid-shell configurations. In the attractive case, odd/even oscillations due to pairing occur simultaneously with deformations in the internal structure of the ground states, as seen from pair correlation functions.