Hexagonal HoMnO3 is a frustrated antiferromagnet (TN = 72 K) ferroelectric (TC = 875 K) in which these two order parameters are coupled. Our neutron measurements of the spin-wave dispersion for the S = 2 Mn3+ on the layered triangular lattice are well described by a two-dimensional nearest-neighbor Heisenberg exchange J = 2.44 meV, and an anisotropy D that is 0.28 meV above the spin-reorientation transition at 40 K and 0.38 meV below. For H ∥ c the magnetic structures and phase diagram have been determined, and reveal additional transitions below 8 K where the ferroelectrically displaced Ho3+ ions are ordered magnetically.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)