The spin–orbit interaction (SOI), mainly manifesting itself in heavy elements and compound materials, has been attracting much attention as a means of manipulating and/or converting a spin degree of ...freedom. Here, we show that a Si metal-oxide- semiconductor (MOS) heterostructure possesses Rashba-type SOI, although Si is a light element and has lattice inversion symmetry resulting in inherently negligible SOI in bulk form. When a strong gate electric field is applied to the Si MOS, we observe spin lifetime anisotropy of propagating spins in the Si through the formation of an emergent effective magnetic field due to the SOI. Furthermore, the Rashba parameter α in the system increases linearly up to 9.8 × 10−16 eV m for a gate electric field of 0.5 V nm−1; that is, it is gate tuneable and the spin splitting of 0.6 μeV is relatively large. Our finding establishes a family of spin–orbit systems.Silicon is a light element with high lattice inversion symmetry, and so is not expected to possess a substantial spin–orbit interaction (SOI), which is desirable for spintronics. Here, a silicon-based heterostructure is demonstrated to have a gate-tuneable Rashba-type SOI.
To augment the magnetoresistance (MR) ratio of n-type non-degenerate Si-based lateral spin valves (Si-LSVs), we modify the doping profile in the Si layer and introduce a larger local strain into the ...Si channel by changing a capping insulator. The highest MR ratio of 1.4% is achieved in the Si-LSVs through these improvements, with significant roles played by a reduction in the resistance-area product of the ferromagnetic contacts and an enhancement of the momentum relaxation time in the Si channel.
We investigate stability of the spin exclusive or (XOR) gate operation in silicon(Si) -based lateral spin devices whose spin transport properties have large variations. The optimum charge current, ...I0, for the spin XOR gate operation is calculated by using the one dimensional spin-drift-diffusion model with variable spin polarization, interface resistance of the ferromagnetic contact, channel length and channel conductivity. I0 is strongly modulated by changing the spin transport parameters particularly under the condition with small spin polarization and short channel length. In contrast, I0 shows constant value irrespective of the interface resistance of one ferromagnetic contact under spin extraction condition. Our results provide a device design guideline for the robust spin XOR gate operation.
A large spin accumulation voltage of more than 1.5 mV at 1 mA, i.e., a magnetoresistance of 1.5 Omega, was measured by means of the local three-terminal magnetoresistance in nondegenerate Si-based ...lateral spin valves (LSVs) at room temperature. This is the largest spin accumulation voltage measured in semiconductor-based LSVs. The modified spin drift-diffusion model, which successfully accounts for the spin drift effect, explains the large spin accumulation voltage and significant bias-current-polarity dependence. The model also shows that the spin drift effect enhances the spin-dependent magnetoresistance in the electric two-terminal scheme. This finding provides a useful guiding principle for spin metal-oxide-semiconductor field-effect transistor operations.
The dependence of the spin accumulation voltage on the electric bias current for a nondegenerate Si-based spin valve was quantitatively investigated using both experiments and calculations. We ...attempted to clarify the reason for the disagreement between the experimentally measured values and those calculated using the spin drift-diffusion equation that takes into account the effect of the spin-dependent interfacial resistance of tunneling barriers, which is an important question in semiconductor spintronics. Unlike the case of metallic spin valves, it was found that the bias dependence of the resistance-area product for the ferromagnet/MgO/Si interface causes a conductance mismatch, and this plays a central role in producing the deviation between the experimental and numerical results.
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