Spin-momentum locking in pseudo-gap phase of Bi2Sr2CaCu2O8+δ bilayer.

We model Bi₂Sr₂CaCu₂O_8+δ(Bi2212) bilayer system by an inversion symmetry broken and time reversal non-invariant Bloch Hamiltonian involving interlayer tunnelling and spin–orbit coupling. The pseudo-gap (PG) phase of the bilayer is assumed to be chiral d-density wave ordered. We have found that the spin–orbit coupling (SOC) is inimical to this order. The presence of SOC was reported earlier in the PG phase in a spin- and angle-resolved photoemission spectroscopic measurement. We also report the theoretical study of the spin-momentum locking, due to the presence of a strong SOC. The non-trivial spin texture in k-space is found tuneable by electric field (and also by intercalation). [ABSTRACT FROM AUTHOR]