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(a) Schematic drawing of non-local measurement configuration of the trilayer-graphene/MgO/Py lateral spin-valve structure. Spin polarized current is injected along the arrow on the left-hand side in trilayer graphene. Pure spin current diffuses in the other side of the graphene and then the spin accumulation is detected at the detector. Magnetic field was applied along the easy axis of the Pyelectrodes during the measurement. (b)Raman spectra of monolayer, trilayer graphene, and graphite. The position of G peak and the spectral features of 2D band confirm the number of atomic layer of the graphene. (c) Optical image of the measurement spin-valve device with electrical contacts for each Py electrode. (d) Room temperature current-voltage (I-V) measurement. The measured interfacial resistance is 2.2 kΩ. Inset shows the schematic picture of the measurement configuration and a scanning electron microscope (SEM) image of LSV fabricated in this study.
Room temperature non-local spin valve measurements of the trilayer graphene lateral spin-valve structures. (a) Typical non-local magnetoresistance with two Py electrodes configuration with and without MgO insulator barrier. The measured non-local magnetoresistance change from parallel to antiparallel configuration is ΔRS = 150 mΩ, which is due to spin injection and transport across the L = 1.2 μm gap between the FM1 and FM2 electrodes. (b) Non-local spin-valve signal and voltage as a function of applied bias current at the injector at T = 300 K. The injector-detector separation is 1.2 μm and the thickness of the MgO layer is 1.0 nm.
Separation and temperature dependence of non-local magnetoresistance measurements in trilayer graphene. The measurements show that the value decreases from 180 mΩ (a) to 110 mΩ (b)as the injector-detector separation increases from 0.9 μm to 1.7 μm at room temperature. At T = 10 K, the value is relatively larger and when the separation increases, there is also a decrease of the value from 630 mΩ (a) to 440 mΩ (b).
Spin diffusion characteristics of trilayer-graphene: injector-detector separation (L) dependence of the . Fittings in 1D spin diffusion equation give a spin diffusion length of 1.5 μm and 2.3 μm at room temperature and T = 10 K, respectively.
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