  We study three-leg-ladder optical lattices loaded with repulsive atomic
Bose-Einstein condensates and subjected to artificial gauge fields. By
employing the plane-wave analysis and variational approach, we analyze the
band-gap structure of the energy spectrum and reveal the exotic swallow-tail
loop structures in the energy-level anti-crossing regions due to an interplay
between the atom-atom interaction and artificial gauge field. Also, we discover
stable discrete solitons residing in a semi-infinite gap above the highest
band, these discrete solitons are associated with the chiral edge currents.
