Abstract
Spin to pseudo-spin conversion by which the non-equilibrium normal sublattice pseudo-spin polarization could be achieved by magnetic field has been proposed in graphene. Calculations have been performed within the Kubo approach for both pure and disordered graphene including vertex corrections of impurities. Results indicate that the normal magnetic field B_z produces pseudo-spin polarization in graphene regardless of whether the contribution of vertex corrections has been taken into account or not. This is because of non-vanishing correlation between the sigma _z and tau _z provided by the co-existence of extrinsic Rashba and intrinsic spin–orbit interactions which combines normal spin and pseudo-spin. For the case of pure graphene, valley-symmetric spin to pseudo-spin response function is obtained. Meanwhile, by taking into account the vertex corrections of impurities the obtained response function is weakened by several orders of magnitude with non-identical contributions of different valleys. This valley-asymmetry originates from the inversion symmetry breaking generated by the scattering matrix. Finally, spin to pseudo-spin conversion in graphene could be realized as a practical technique for both generation and manipulation of normal sublattice pseudo-spin polarization by an accessible magnetic field in a easy way. This novel proposed effect not only offers the opportunity to selective manipulation of carrier densities on different sublattice but also could be employed in data transfer technology. The normal pseudo-spin polarization which manifests it self as electron population imbalance of different sublattices can be detected by optical spectroscopy measurements.
Highlights
Spin to pseudo-spin conversion by which the non-equilibrium normal sublattice pseudo-spin polarization could be achieved by magnetic field has been proposed in graphene
A and B sublattices, the out of plane operator τz indicates sublattice quantum number A or B. Each of these sublattices can be described by its own Bloch wave function denoted by ψA and ψB . ψA/B remains invariant under the action of τz in plane pseudo-spin operators τx(y) changes the state of electrons wave function from ψA to ψB and vice versa. η is the valley index that gets +1, −1 values for the K and K′ points respectively. so indicates the strength of intrinsic spin–orbit interaction (SOI) and the strength of externally induced inversion asymmetry that leads to extrinsic Rashba SOI is identified by R1
It should be noted that we have demonstrated how non-equilibrium pseudo-spin polarization could be produced by normal magnetic filed by exploiting of non-vanishing correlation between the spin of electrons and pseudo-spin texture in graphene
Summary
Spin to pseudo-spin conversion by which the non-equilibrium normal sublattice pseudo-spin polarization could be achieved by magnetic field has been proposed in graphene. Spin to pseudo-spin conversion in graphene could be realized as a practical technique for both generation and manipulation of normal sublattice pseudo-spin polarization by an accessible magnetic field in a easy way This novel proposed effect offers the opportunity to selective manipulation of carrier densities on different sublattice and could be employed in data transfer technology. The conversion between different quantum numbers with different dephasing and diffusive lengths could be employed in the future data transfer technologies to obtain an optimized data transmission process In this way, capability of charge-spin interconversion which arises from intrinsic spin–orbit interaction (SOI) has become one of the key phenomena in this field recently. The SHE and inverse SHE, could be considered as two different efficient ways for generation and detection of pure spin current that carries a net angular m omentum[4,8]
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