Competition between the inter- and intra-sublattice interactions inYb2V2O7

Abstract

We studied the magnetic properties of single-crystal ${\mathrm{Yb}}_{2}{\mathrm{V}}_{2}{\mathrm{O}}_{7}$ using dc and ac susceptibility measurements, elastic and inelastic neutron-scattering measurements, and linear spin-wave theory. The experimental data show a ferromagnetic ordering of ${\mathrm{V}}^{4+}$ ions at 70 K, a short-range ordering of ${\mathrm{Yb}}^{3+}$ ions below 40 K, and finally a long-range noncollinear ordering of ${\mathrm{Yb}}^{3+}$ ions below 15 K. With external magnetic field oriented along the [111] axis, the Yb sublattice experiences a spin flop transition related to the ``three-in one-out'' spin structure. By modeling the spin-wave excitations, we extract the Hamiltonian parameters. Our results confirm that although the extra inter-sublattice Yb-V interactions dramatically increase the Yb ordering temperature to 15 K, the intra-sublattice Yb-Yb interactions, based on the pyrochlore lattice, still stabilize the Yb ions' noncollinear spin structure and spin flop transition.