(Laurentian University of Sudbury, 2015-02-24) Rodger, Clifford John
Electron spin resonance (ESR) is an important experimental technique. A comprehensive theory of ESR has been di cult to establish, and as such several di erent approximations
are used to predict and explain experimental results. This thesis applies the bond-mean-
eld theory to the problem of ESR frequency shift for the one-dimensional antiferromagnetic
Heisenberg spin chain with uniaxial exchange anisotropy. We use this theory to calculate
the ESR resonance frequency shift as a function of temperature and magnetic eld. We
perform numerical calculations using the expression obtained. These results are compared
to existing results in the literature; they are in broad agreement with theoretical results such
as those of Oshikawa and A eck obtained via bosonisation, but they show discrepancies
with experimental results. We agree with the theoretical authors that the discrepancy is due to our use of the simplest-case interaction model.
