Thermodynamic Properties of 1d Heisenberg Model. Magnetic Moment of Spinon

The one dimensional spin 1/2 Heisenberg antiferromagnet is considered using a simple quasiparticle picture - an 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 computations and conformal field theory calculations. It is hypothesised that the magnetic moment of the kink $g_{kink}=\sqrt{2}g_{electron}$.