Current-induced spin polarization in InGaAs epilayers with varying doping densities

Current-induced spin polarization (CISP) is a phenomena in which an applied electric field produces a bulk spin polarization in the plane of the sample. As this is thought to arise from the spin-orbit coupling, it was originally predicted that the magnitude of CISP should be proportional to the spin-orbit (SO) splitting [1]. However, crystal axis-dependent measurements of the CISP and SO fields showed a negative differential relationship between these two quantities [2]. To develop a phenomenological understanding of the factors affecting the magnitude of CISP, we performed measurements on three In$_{0.025}$Ga$_{0.975}$As epilayers, Si-doped at 0.67, 9.6, and 14.1 x 10$^{17}$ cm$^{-3}$. We will discuss the effects of the doping density and electron mobility on the magnitudes of the SO fields and CISP. [1] V. Edelstein, Solid State Commun. \textbf{73}, 233 (1990). [2] Norman, B. M., et al., Phys. Rev. Lett. \textbf{112}, 056601 (2014).