Self-consistent spin wave analysis of the magnetization plateau in triangular antiferromagnet

We investigate theoretically the 1/3 magnetization plateau of the triangular-lattice Heisenberg antiferromagnet at zero temperature. Using the self-consistent spin-wave analysis, we show that the 1/3 plateau is stabilized in a finite range of magnetic fields: 0.844 < H/3SJ < 1.368 for S = 1/2. By analyzing the Bose condensation of magnons, we demonstrate that the magnetization curve has logarithmic singularities at the both ends of the plateau and determine the prefactor of the singularity up to the leading order in 1/S.