Spin relaxation through lateral spin transport in heavily doped 
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-type silicon

Ishikawa, M.; Oka, Tetsuo; Fujita, Y.; Sugiyama, H.; Saito, Y.; Hamaya, Kohei

doi:10.1103/physrevb.95.115302

Cited by 39 publications

(47 citation statements)

References 46 publications

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“…Finally, we compare our data to previous work on non-local spin-transport devices, specifically, by Suzuki et al 12 who first reported non-local spin transport in Si devices up to room temperature, and by Ishikawa et al 16 , who only very recently published data with, to the best of our knowledge, the largest non-local spin signals for degenerately-doped Si to date. We compare the published experimental data 12,16 of the spin signals converted into a spin-RA product (units of Ωµm 2 ), instead of previously extracted values of ∆µ or P , in order to make the comparison insensitive to differences in the theoretical analysis used to extract parameters from the data. The comparison, displayed in Fig.…”

Section: E Role Of Injector Width and Spin-diffusion Lengthsupporting

confidence: 67%

“…In this geometry, one ferromagnetic contact is used as injector to induce a spin accumulation in the semiconductor channel, and the spin accumulation is detected using a second ferromagnetic electrode placed close to the point of injection at a distance comparable to or smaller than the characteristic spin-transport length (the spin-diffusion length, given by L SD = √ D τ s , where D is the diffusion constant). Indeed, using such non-local devices, the electrical injection, transport and detection of spins in heavily-doped n-type silicon have been achieved [10][11][12][13][14][15][16][17] , including at room temperature. Unfortunately, the induced spin accumulation was very small and the detected spin signals (in the µV range) are about two orders of magnitude smaller than expected.…”

Section: Introductionmentioning

confidence: 99%

“…Unfortunately, the induced spin accumulation was very small and the detected spin signals (in the µV range) are about two orders of magnitude smaller than expected. Although the reason has not been clearly identified, within the standard theory for spin injection and diffusion 8,9,18,19 the small spin accumulation translates into a small tunnel spin polarization of only 5 -10 % for the Fe/MgO tunnel contacts used for spin injection and detection [10][11][12][13][14][15][16][17] . However, much larger values (50% or higher) are expected for crystalline Fe/MgO(001) tunnel contacts that are notorious for their large tunnel spin polarization [20][21][22] arising from symmetry-based spin filtering 23,24 .…”

Section: Introductionmentioning

confidence: 99%

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Giant Spin Accumulation in Silicon Nonlocal Spin-Transport Devices

et al. 2017

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Although the electrical injection, transport and detection of spins in silicon have been achieved, the induced spin accumulation was much smaller than expected and desired, limiting the potential impact of Si-based spintronic devices. Here, using non-local spin-transport devices with an n-type Si channel and Fe/MgO magnetic tunnel contacts, we demonstrate that it is possible to create a giant spin accumulation in Si, with the spin splitting reaching 13 meV at 10 K and 3.5 meV at room temperature. The non-local spin signals are in good agreement with a numerical evaluation of spin injection and diffusion that explicitly takes the size of the injector contact into account. The giant spin accumulation originates from the large tunnel spin polarization of the Fe/MgO contacts (53 % at 10 K and 18 % at 300 K), and the spin density enhancement achieved by using a spin injector with a size comparable to the spin-diffusion length of the Si. The ability to induce a giant spin accumulation enables the development of Si spintronic devices with a large magnetic response.

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Section: E Role Of Injector Width and Spin-diffusion Lengthsupporting

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Giant Spin Accumulation in Silicon Nonlocal Spin-Transport Devices

et al. 2017

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“…In the so-called nonlocal spin transport devices 19,20 , one employs a four-terminal measurement configuration in which one ferromagnetic contact is biased in order to induce a spin accumulation in the nonmagnetic channel, whereas the second ferromagnetic contact, the spin detector, remains unbiased. The spin signals observed in such nonlocal devices with tunnel contacts [21][22][23][24][25][26][27][28][29] are well described by the theory for spin injection and detection in the linear response regime 13,30 . Consequently, nonlocal devices have been instrumental to prove and understand spin injection and transport in a wide variety of materials, although they are of little direct technological relevance.…”

Section: Introductionmentioning

confidence: 76%

Nonlinear Electrical Spin Conversion in a Biased Ferromagnetic Tunnel Contact

et al. 2018

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The conversion of spin information into electrical signals is indispensable for spintronic technologies. Spin-to-charge conversion in ferromagnetic tunnel contacts is well-described using linear (spin-)transport equations, provided that there is no applied bias, as in nonlocal spin detection. It is shown here that in a biased ferromagnetic tunnel contact, spin detection is strongly nonlinear. As a result, the spin-detection efficiency is not equal to the tunnel spin polarization. In silicon-based 4-terminal spin-transport devices, even a small bias (tens of mV) across the Fe/MgO detector contact enhances the spin-detection efficiency to values up to 140 % (spin extraction bias) or, for spin injection bias, reduces it to almost zero, while, parenthetically, the charge current remains highly spin polarized. Calculations reveal that the nonlinearity originates from the energy dispersion of the tunnel transmission and the resulting nonuniform energy distribution of the tunnel current, offering a route to engineer spin conversion. Taking nonlinear spin detection into account is also shown to explain a multitude of peculiar and puzzling spin signals in structures with a biased detector, including two-and three-terminal devices, and provides a unified, consistent and quantitative description of spin signals in devices with a biased and unbiased detector.

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“…We propose that the length scale for Rashba spin-orbit coupling can be as large as the spin diffusion length in semiconductor or normal metal, which is supported by the observed experimental results. The observed Rashba effect may challenge the non-local spin transport measurement [1,3,40] in Si since Rashba effect may enhance the spin polarization.…”

Section: Inversionmentioning

confidence: 97%

Spin-Hall effect and emergent antiferromagnetic phase transition in n-Si

Lou

Kumar

2018

Journal of Magnetism and Magnetic Materials

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Spin current experiences minimal dephasing and scattering in Si due to small spin-orbit coupling and spin-lattice interactions is the primary source of spin relaxation. We hypothesize that if the specimen dimension is of the same order as the spin diffusion length then spin polarization will lead to non-equilibrium spin accumulation and emergent phase transition. In n-Si, spin diffusion length has been reported up to 6 µm. The spin accumulation in Si will modify the thermal transport behavior of Si, which can be detected with thermal characterization. In this study, we report observation of spin-Hall effect and emergent antiferromagnetic phase transition behavior using magneto-electro-thermal transport characterization. The freestanding Pd (1 nm)/ Ni 80 Fe 20 (75 nm)/ MgO (1 nm)/ n-Si (2 µm) thin film specimen exhibits a magnetic field dependent thermal transport and spin-Hall magnetoresistance behavior attributed to Rashba effect. An emergent phase transition is discovered using self-heating 3w method, which shows a diverging behavior at 270 K as a function of temperature similar to a second order phase transition. We propose that spin-Hall effect leads to the spin accumulation and resulting emergent antiferromagnetic phase transition.We propose that the length scale for Rashba effect can be equal to the spin diffusion length and two-dimensional electron gas is not essential for it. The emergent antiferromagnetic phase transition is attributed to the site inversion asymmetry in diamond cubic Si lattice.

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Spin relaxation through lateral spin transport in heavily doped n -type silicon

Cited by 39 publications

References 46 publications

Giant Spin Accumulation in Silicon Nonlocal Spin-Transport Devices

Giant Spin Accumulation in Silicon Nonlocal Spin-Transport Devices

Nonlinear Electrical Spin Conversion in a Biased Ferromagnetic Tunnel Contact

Spin-Hall effect and emergent antiferromagnetic phase transition in n-Si

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