The spin-wave spectrum in a system with triple-$\overrightarrow{\mathrm{q}}$ magnetic structure is calculated. The spin waves differ distinctly from those in the corresponding single-$\overrightarrow{\mathrm{q}}$ structure, but agree with the excitations observed by Lander and Stirling in uranium antimonide (USb). Their experiments thus directly verify that the spins in USb are ordered in the triple-$\overrightarrow{\mathrm{q}}$ structure.

• Received 22 December 1980

DOI:https://doi.org/10.1103/PhysRevB.23.6180