S. Gluzman, ONE-DIMENSIONAL FRUSTRATED HEISENBERG-ANTIFERROMAGNET OF SPIN 1 2 IN A STRONG MAGNETIC-FIELD/, Physical review. B, Condensed matter, 49(17), 1994, pp. 11962-11966
The properties of the one-dimensional antiferromagnet of spin 1/2 in a
strong magnetic field h with nearest- and next-nearest-neighbor inter
actions are studied in terms of the equivalent Bose-gas problem. We fi
nd that below the first critical field h(cu) a phase with a gap in the
elementary excitation spectrum and corresponding plateau in the magne
tization curve should exist due to the two-particle attraction in the
vicinity of the commensurate wave number p0u = pi. In the interval bet
ween the first and second critical fields h(cu) < h < h(cf), the syste
m behaves as the one-dimensional Bose gas with particle repulsion and
the magnetization has a typical square-root dependence on field.