Manipulation of Spin Splitting in Two-Dimensional Lead Bromide Perovskite Rashba Piezoelectrics

In this work, a two-dimensional perovskite Rashba piezoelectrics (TPRP) is proposed by a density functional theory study. The Rashba spin splitting in TPRP is optimized via the dipole moment of A-site organic cations and the atom displacement in inorganic [PbBr6](2-) octahedrons. The Rashba spin splitting energy and the corresponding parameter (alpha(R)) of unstrained (ATHP)(2)PbBr4 TPRP are calculated as 41 meV and 0.65 eV.angstrom, respectively. This value should be the highest for any Br-based lead halide perovskites to the best of our knowledge. In addition, the value of alpha(R), responsible for the piezoelectric potential, is further tuned from 0.41 to 0.81 eV.angstrom via adjusting the local polarization by applying a strain from +0.01 to -0.01 along the c axis.