The energy width ${\Gamma }_k$ due to exchange scattering of magnons in a magnetic field is of the form ${\Gamma }_k\sim k^2{\epsilon }_{k}F(k^2, \frac{\mu H}{d{k}^2})$ for the energy ${\epsilon }_k=\mu H+D{k}^2\ll k_{B}T$ in a ferromagnet. The factor $F(k^2, \frac{\mu H}{D{k}^2})$ is related to the availability of phase space for scattering and is shown to be regular at $k=0\mathrm{}$ for any nonzero magnetic field, in contrast to the well-known logarithmic singular behavior for $H=0\mathrm{}$. The dependence of ${\Gamma }_k$ on $H$ is calculated and discussed.

Close

PrevNext

View figure in article