*

Magnon current induced spin torque, due to its minimized energy dissipation, has opened up a new arena for energy efficient magnetization switching, where spin-magnon current interconversion and pioneering work on magnon mediated spin torque switching of ferromagnet have been reported. Multiferroic material BiFeO₃, with a magneto-electric coupling between ferroelectric and antiferromagnetic orders, is a prefect candidate for studying magnon current assisted spin torque as well as spontaneous ferroelectric polarization dependent magnon transport. A study has been carried out on FM/BiFeO₃/SOC trilayer, showing that BiFeO₃ has a strong tunability on the spin current transmission efficiency across the BiFeO₃ mediator. An insertion of 1.5-unit cell of SrRuO₃, which has proven to be able to change the spontaneous polarization of BiFeO₃, could turn off the spin current transmission across BiFeO₃ via magnon by 30%.