Comment on the magnetic circular dichroism spectrum of MnF2

A recent article by Shatwell and McCaffery questioned the usefulness of magnetic-circular-dichroism (MCD) techniques applied to Mn${\mathrm{F}}_2$. We show that the Zeeman splitting of the purely excitonic lines tests for sample to sample variations which would be reflected in the MCD spectrum. We present Zeeman and MCD data which show long-term reproducibility and suggest experimental variables which may have affected Shatwell and McCaffery's results.