Competition between the inter- and intra-sublattice interactions in Yb$_{2}$V$_{2}$O$_{7}$

We studied single crystals of Yb$_{2}$V$_{2}$O$_{7}$ using dc and ac susceptibility measurements, elastic and inelastic neutron scattering measurements, and linear spin wave theory. The experimental data shows a ferromagnetic ordering of V$^{4+}$ ions at 70 K, a short-range ordering of Yb$^{3+}$ ions below 40 K, and finally a long-range non-collinear ordering of 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 increases the Yb ordering temperature to 15 K, the intra-sublattice Yb-Yb interactions, based on the pyrochlore lattice, still stabilize the Yb ions' non-collinear spin structure and spin flop transition.