First-principles Study of Rashba Spin Splitting at Strained SrTiO3(001) Surfaces

We investigated the Rashba spin splittings in a compressive-strained SrTiO$_3$(001) ultra thin-film using first-principles calculations. The effect of the polarization due to the compressive strain leads to the 2DEG with large Rashba spin splittings, where the sheet carrier density is of the same order of magnitude as that of the heterostructure LaAlO$_3$/SrTiO$_3$ ($\sim10^{14}$ cm$^{-2}$). Some localized surface states (SSs) show the giant Rashba coefficient $\alpha_R$ larger than 100 meV$\cdot$\AA.