2013/03/31 by Takuya Susuki, Nobuyuki Kurita, Takuya Tanaka +4 · 1 citation
Physics and Astronomy · #cond-mat.str-el
paper · pdf · doi:10.1103/physrevlett.110.267201
published as Phys. Rev. Lett. 110, 267201 (2013) · 5 pages, 4 figures
arxiv created 2013/06/25 · arxiv updated 2015/06/15
We have performed high-field magnetization and ESR measurements on Ba3CoSb2O9 single crystals, as a representative two-dimensional spin-1/2 Heisenberg antiferromagnet on a uniform triangular lattice, and have determined all the magnetic parameters. For an applied magnetic field H parallel to the ab-plane, the entire magnetization curve including the plateau at one-third of the saturation magnetization (Ms) is in excellent agreement with the results of theoretical calculations except an anomaly near (3/5)Ms, indicative of an additional field-induced transition. However, for H ∥ c, the magnetization curve exhibits a cusp near Ms/3. Paramagnetic resonance signals above the Néel temperature indicate the nearly isotropic g-factor. A detailed analysis of the collective ESR modes observed in the ordered state, combined with the magnetization process, provides evidence of the weak easy-plane anisotropy.