Neutron Scattering Study of Magnetic Field Tuned Non-Reciprocal Magnons in α-Cu₂V₂O₇

Non-reciprocal magnons—collective spin excitations that propagate differently in opposite directions—are of growing interest in condensed matter physics. We report neutron scattering studies of these excitations in the antiferromagnet α-Cu₂V₂O₇ under high magnetic fields applied along the crystallographic a- and c-axes. For fields along the a-axis, the system undergoes a spin flip-flop transition at 6.5 T, accompanied by incommensurate magnetic Bragg peaks and reciprocal magnons, reflecting a field-driven reorganization of the spin structure.  Along the c-axis, no magnetic phase transition occurs; instead, the magnon gap increases and a possible band splitting emerges near the crossing point, in agreement with theoretical predictions.  These results reveal how anisotropic and antisymmetric spin interactions control non-reciprocal magnon behavior. Together, experiment and theory provide new insight into field-tuned spin dynamics in α-Cu₂V₂O₇ and broaden the understanding of non-reciprocal phenomena in quantum magnets.