title: Experimental realization of a spin-1/2 triangular-lattice Heisenberg antiferromagnet.
abstract: We report the results of magnetization and specific heat measurements on Ba{3}CoSb{2}O{9}, in which the magnetic Co{2+} ion has a fictitious spin 1/2, and provide evidence that a spin-1/2 Heisenberg antiferromagnet on a regular triangular lattice is actually realized in Ba{3}CoSb{2}O{9}. We found that the entire magnetization curve including the one-third quantum magnetization plateau is in excellent quantitative agreement with the results of theoretical calculations. We also found that Ba{3}CoSb{2}O{9} undergoes a three-step transition within a narrow temperature range.
authors.affiliation: Department of Physics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Shirata
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Tanaka
authors.forename: Akira
authors.initials: A
authors.lastname: Matsuo
authors.forename: Koichi
authors.initials: K
authors.lastname: Kindo