Stacking the Collinear Magnetic Phases of the Geometrically-Frustrated Antiferromagnet CuFeO$_{2}$

The correct stacking of hexagonal layers is used to obtain accurate estimates for the exchange and anisotropy parameters of the geometrically-frustrated antiferromagnet CuFeO$_{2}$. Those parameters are highly constrained by the stability of a collinear metamagnetic phase between fields of 13.5 and 20 T. Constrained fits of the spin-wave frequencies of the ``up up down down'' phase below 7 T are used to identify the magnetic unit cell of the metamagnetic ``up up up down down'' phase, which contains two hexagonal layers and 10 Fe$^{3+}$ spins. The resulting exchange parameters are much smaller than those obtained from an unconstrained fit of the zero-field spin-wave data and successfully describe not only the main branch of spin-wave excitations but also the spin-wave excitations of the two twins in the (H,K,0) plane [1]. Research sponsored by the Division of Materials Sciences and Engineering, U.S. Department of Energy under contract with UT-Battelle, LLC. \\[0pt] [1] R.S. Fishman, F. Ye, J.A. Fernandez-Baca, J.T. Haraldsen, and T. Kimura, \textit{Phys. Rev. B} \textbf{78}, 140407 (2008).