Antiferromagnetic Dispersion Relations and Nature of Magnon Pressure

Abstract

We derive higher-order corrections in the magnon dispersion relations for two-and three-dimensional antiferromagnets exposed to magnetic and staggered fields that are mutually aligned. "Dressing" the magnons is the prerequisite to separate the low-temperature representation of the pressure into a piece due to noninteracting magnons and a piece that corresponds to the magnon-magnon interaction. Both in two and three spatial dimensions, the interaction in the pressure turns out to be attractive. While concrete figures refer to the spin-1 2 square-lattice and the spin-1 2 simple cubic lattice antiferromagnet, our results are valid for arbitrary bipartite geometry.