Physical review. B, Condensed matter
Field-theory treatment of the Heisenberg spin-1 chain
Alexei M. Tsvelik
Abstract
We suggest a new field-theory treatment of the Heisenberg spin-1 chain with a single-ion anisotropy as a theory of three Majorana (real) fermions. We calculate the static and dynamic magnetic susceptibilities. We show that our results are in a good agreement with the experimental data for NENP [Ni(${\mathrm{C}}_{2}$${\mathrm{H}}_{8}$${\mathrm{N}}_{2}$)${\mathrm{NO}}_{2}$${\mathrm{ClO}}_{4}$] compound. In particular, we eliminate the reported contradiction between excitation gaps deduced from high-field magnetization measurements and neutron scattering.