Generation and detection of dissipationless spin current in Si

The generation and detection of spin current without ferromagnetic or exotic/scarce materials are two the biggest challenges for spintronics devices. In this study, we report a solution to the two problems of spin current generation and detection in Si. Using non-local measurement, we experimentally demonstrate the generation of helical dissipationless spin current using intrinsic spin-Hall effect. The intrinsic spin Hall effect is attributed to the site-inversion asymmetry in the diamond cubic lattice of Si. The spin to charge conversion in Si is insignificant due to weak spin-orbit coupling. For the efficient detection of spin current, we report spin to charge conversion at the MgO (1nm)/Si (2 µm) (p-doped and n-doped) thin film interface. Using x-ray photoemission spectroscopy, we determined that the interface consists of MgO/Mg/SiO₂. The oxygen deficient interface leads to a two-dimensional electron system. The structure inversion asymmetry at the interface leads to Rashba spin orbit coupling and efficient spin to charge conversion observed in this work. The existence of spin current in Si is verified from coercivity reduction in Co/Pd multilayer from spin-orbit torque generated by spin current from Si.