Field-induced inhomogeneous ground states of antiferromagnetic ANNNI chains

Finite-size effects are studied in ground states of antiferromagnetic (AF) ANNNI chains in a field. It is shown that field can induce a variety of inhomogeneous states in finite chains. They are composed of two shifted AF states with the kink at their junction and are highly degenerate with respect to the kink position. The phase diagram field-exchange ratio for finite chains is presented.