Tuning Anisotropic Magnon Transport in Multiferroic Oxides by Crystal Symmetry

Abstract Magnon spin current can transport in magnetically ordered insulators without substantial heat dissipation, holding great potential for future spintronic devices. The electric‐field control of magnons has garnered recent interest in magnon transport in BiFeO 3 (BFO), a benchmark multiferroic with coupled ferroelectric and antiferromagnetic orders. However, the mechanisms that govern the magnon transport across BFO in heterostructures remain poorly understood. Here, the tuning of anisotropic magnon transport is reported by crystal symmetry in BFO‐based system. The single‐domain rhombohedral ferroelectric BFO exhibits a spin‐cycloid structure and a relatively weak anisotropy of magnon transport. In contrast, a pronounced uniaxial anisotropy of magnon transport is established in the orthorhombic antiferroelectric La‐doped BFO with a collinear antiferromagnetic order, which only transmits magnon current with spin polarization along the Néel vector. Moreover, increasing La concentration reduces the propagation length of magnon. The findings pave a new pathway to realize the electric‐field‐controlled magnon transport for highly efficient magneto‐electric spin‐orbit (MESO) devices.