Observation of Magnon Spin Transport in BiFeO₃ Thin Films

Abstract

Magnon, a quanta of spin waves, can transport in magnetically ordered insulators without substantial heat dissipation. The recently demonstrated magnon‐mediated spin torque through antiferromagnetic insulators is regarded as a highly efficient approach for electrical manipulation of magnetization. To control the magnon transport in antiferromagnets, a very large magnetic field is required, since antiferromagnets show immunity to external magnetic disturbance. The antiferromagnetic order can be electrically controlled in multiferroic materials via the magnetoelectric coupling between the antiferromagnetic and ferroelectric orders. Here, we report the experimental observation of magnon spin transport through multiferroic BiFeO3 thin films in SrRuO3/BiFeO3/NiFe tri‐layers at room temperature. We find highly efficient magnon current transmission through BiFeO3 thin film with a thickness exceeding 80 nm by the spin pumping measurement. The magnon spin‐torque efficiency in the tri‐layers measured by the spin‐torque ferromagnetic resonance is comparable with that in the SrRuO3/NiFe bilayer. This results suggest multiferroic BiFeO3 to be an excellent platform for investigating the antiferromagnetic magnon transport and developing magnonic devices.

Visualizing Nanoscale Interlayer Magnetic Interactions and Unconventional Low‐Frequency Behaviors in Ferromagnetic Multishelled Structures

“…Various types of ferromagnetic materials with different structures have been reported, and their magnetic properties can be regulated by structural design. [ 35–39 ] However, the intershell magnetic interactions of ferromagnetic materials to guide structural design has not been systematically simulated to guide the structural design. To address this problem, micromagnetic simulations of ferromagnetic materials were performed.…”

Voltage control of multiferroic magnon torque for reconfigurable logic-in-memory

“…A charge current pulse (I w ) flowing through the channel induces spin accumulation with polarization at the multiferroic bottom interface through the spin-Hall effect or the Rashba–Edelstein effect 35 , 36 , which can excite antiferromagnetic magnon modes depending on the orientation of , as the spin injection transmitted to magnons is proportional to 37 , 38 . As the magnons (carrying the spin-polarized angular momentum from the bottom layer) diffuse across the multiferroic layer to the ferromagnet’s bottom interface, they exert the magnon torque to control the magnetic moment 17 , 39 , 40 , enabling non-volatile writing of spin information to multiple cells on the current channel in parallel. For magnon logic operations, a gate voltage (V G ) pulse is applied across the multiferroic BiFeO 3 to switch , which can modulate the antiferromagnetic structure as schematically shown in the pseudo-cubic unit cell of BiFeO 3 (Fig.…”

Tunable magnons of an antiferromagnetic Mott insulator via interfacial metal-insulator transitions

“…Hetero-interfaces between two different materials can provide model systems for investigating the relation between external stimuli and collective spin waves. Examples are the effects of lattice strain 7 , interfacial coupling, and charge transfer on magnons 8,9 and their spin currents [10][11][12] . In particular, interfaces between an antiferromagnetic insulator and a metal have been considered for novel spin-charge conversion 13,14 .…”