Magnetic Excitations in a Possible Quantum Ferromagnet

The proposed experiment is to measure in considerable detail the magnetic excitations inY2V2O7. Bulk measurements on this pyrochlore magnet show that it is a ferromagnet with a transition temperature close to 70 K. Like its counterpart, Lu2V2O7, we expect Y2V2O7 to have significant Dzyaloshinskii-Moriya exchange (DM) leading to a nontrivial Berry curvature and unusual thermal transport properties as well as characteristic magnon damping. Even more interesting, Y2V2O7 is a strong candidate to host Weyl points in its magnon band structure which have not been observed before. Their presence would imply the presence of topologically-protected surface states and potentially other unusual properties. Our experiment will enable us to carry out a complete characterization of the magnetic exchange in this material and potentially observe the magnetic Weyl points.