[16p-D704-1~18] 10.4 Spintronics in semiconductor, topological material, superconductor, and multiferroics

[16p-D704-12] Spin polarization and magnetoresistance in a back-gated spin MOSFET structure with Fe/Mg/MgO/SiO_x/n⁺-Si junctions

〇(PC)Shoichi Sato^1,2, Masaaki Tanaka^1,2, Ryosho Nakane¹ (1.Tokyo Univ., 2.CSRN)

Keywords:spin injection, SpinMOSFET, Silicon

To enhance the MR ratio of Si-based spin MOSFETs, Fe/Mg/MgO/SiO_x/n⁺-Si junctions are very promising because they can generate a high spin polarization P_S of electrons. In this study, spin MOSFET device structure having Fe(3 nm)/Mg(1 nm)/MgO(1.2 nm)/SiO_x(0.2 nm)/n⁺-Si for the source (S) and drain (D) junctions were measured. Spin polarization P_S and the MR ratio were estimated from the spin-valve signals and they were analyzed as a function of the junction voltage drop V_J. We found that P_S has a positive peak value of 48% at |V_J| = ~0.3 V, on the other hand, the MR ratio has a positive peak at |V_J| = ~0.8 V. Hence, the device does not fully exploit the potential of the junction and this phenomenon is caused by the tradeoff between the P_S - V_J relationship and the junction resistance-area product. The strategy for enhancement of the MR ratio is to realize a high P_S value in a tunnel injector/detector junction having a very low resistance-area product.