Electric-Controlled Valley Pseudomagnetoresistance in Graphene with Y-Shaped Kekulé Lattice Distortion.

We propose a new method for regulating valley pseudomagnetoresistance in ballistic graphene-based valley field-effect transistors by taking into account the Y-shaped Kekulé lattice distortion and electric barrier. The device involves valley injection and valley detection by ferromagnetic-strain source and drain. The valley manipulation in the channel is achieved via the Y-shaped Kekulé lattice distortion and electric barrier.

Electric Field Controlled Indirect-Direct-Indirect Band Gap Transition in Monolayer InSe.

Electronic structures of monolayer InSe with a perpendicular electric field are investigated. Indirect-direct-indirect band gap transition is found in monolayer InSe as the electric field strength is increased continuously. Meanwhile, the global band gap is suppressed gradually to zero, indicating that semiconductor-metal transformation happens.

Tunable Dirac points and high spin polarization in ferromagnetic-strain graphene superlattices.

Spin-dependent energy bands and transport properties of ferromagnetic-strain graphene superlattices are studied. The high spin polarization appears at the Dirac points due to the presence of spin-dependent Dirac points in the energy band structure. A gap can be induced in the vicinity of Dirac points by strain and the width of the gap is enlarged with increasing strain strength, which is beneficial for enhancing spin polarization.

Helical edge states and edge-state transport in strained armchair graphene nanoribbons.

A helical type edge state, which is generally supported only on graphene with zigzag boundaries, is found to also appear in armchair graphene nanoribbons in the presence of intrinsic spin-orbit coupling and a suitable strain. At a critical strain, there appears a quantum phase transition from a quantum spin Hall state to a trivial insulator state. Further investigation shows that the armchair graphene nanoribbons with intrinsic spin-orbit coupling, Rashba spin-orbit coupling, effective exchange fields and strains also support helical-like edge states with a unique spin texture.

Valley precession and valley polarization in graphene with inter-valley coupling.

We theoretically investigate the valley precession and valley polarization in graphene under inter-valley coupling. Our results show that the inter-valley coupling can induce valley polarization in graphene and also precess valleys in real space in a manner similar to the Rashba spin-orbit interaction rotating spins. Moreover, using strain modulation, we can achieve high valley polarization with large valley-polarized currents.

Edge states and quantum phase transition in graphene under in-plane effective exchange fields.

We investigated the edge states and quantum phase transition in graphene under an in-plane effective exchange field. The result shows that the combined effects of the in-plane effective exchange field and a staggered sublattice potential can induce zero-energy flat bands of edge states. Such flat-band edge states can evolve into helical-like ones in the presence of intrinsic spin-orbit coupling, with a unique spin texture.

Full Valley and Spin Polarizations in Strained Graphene with Rashba Spin Orbit Coupling and Magnetic Barrier.

We propose a graphene-based full valley- and spin-polarization device based on strained graphene with Rashba spin orbit coupling and magnetic barrier. The underlying mechanism is the coexistence of the valley and single spin band gaps in a certain Fermi energy. By aligning the Fermi energy in the valley and single spin band gaps, remarkable valley- and spin-polarization currents can be accessed.