Exchange narrowing of the phonon contribution to the electron spin resonance line width in exchange-coupled magnetic insulators.
In this paper we extend earlier calculations of the phonon contribution to the electron spin resonance line width at high temperatures in exchange-coupled magnetic insulators. We show that the one-phonon contribution is exchange-narrowed, similar to the static anisotropy contribution. The effect of the exchange narrowing is to limit contributing phonons to those modes whose energies are less than a cutoff, γ(max), that is proportional to the exchange interaction. Linear-T behavior in the line width occurs when kBT is greater than γ(max).
Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, USA.
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Huber