2011/04/12 by K. Tomiyasu, H. Ueda, M. Matsuda +3 · 1 citation
Physics and Astronomy · #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.84.035115
published as Phys. Rev. B 84, 035115 (2011) · 5 pages, 2 figures
arxiv created 2011/04/12 · arxiv updated 2011/08/18
A hexamer-type spin excitation seen in spinel chromates ACr2O4 (A = Mg, Zn, or Cd) is the representative spin-liquid-like state caused by geometrical frustration. To clarify an origin of the state, we comparatively studied spin excitations in an isomorphic material HgCr2O4 by inelastic neutron scattering, and observed a different molecular-type excitation. Numerical analyses performed using model Hamiltonians suggest that these two types of spin excitations originate from a spin-3/2 molecular singlet hidden in a magnetically ordered phase. The difference between the molecular types is explained by the difference in the kind of exchange interactions occurring in the chromates.