Magnetic moment of a spinon and thermodynamic properties of the one-dimensional Heisenberg model

The one-dimensional spin-$\frac{1}{2}$ Heisenberg antiferromagnet is considered using a simple quasiparticle picture: a weakly interacting Fermi gas of kinks. Using this picture, the low-temperature heat capacity, and the magnetic susceptibility with logarithmic field and temperature corrections are derived. The results obtained are in agreement with previous Bethe ansatz and conformal field-theory calculations. We demonstrate from comparison with previous calculations that the magnetic moment of the kink $g_{\mathrm{kink}}=\sqrt{2}{g}_{\mathrm{electron}}.$