Gate-tunable valley-filter based on suspended graphene with double magnetic barrier structures

• Interplay between real and pseudo-magnetic fields leads to strain-dependent tunneling.
• Ballistic transport through suspended graphene exhibits valley-dependent features.
• Valley-dependent transport through suspended graphene can be tunable by gate voltage.
• Gate-tunable valley-filtering may holds promise for realizing graphene valleytronics.

We theoretically investigate the effects of strain-induced pseudomagnetic fields on the transmission probability and the ballistic conductance for Dirac fermion transport in suspended graphene. We show that resonant tunneling through double magnetic barriers can be tuned by strain in the suspended region. The valley-resolved transmission peaks are apparently distinguishable owing to the sharpness of the resonant tunneling. With the specific strain, the resonant tunneling is completely suppressed for Dirac fermions occupying the one valley, but the resonant tunneling exists for the other valley. The valley-filtering effect is expected to be measurable by strain engineering. The proposed system can be used to fabricate a graphene valley filter with the large valley polarization almost 100%.