Role of MgO barriers for spin and charge transport in Co/MgO/graphene non-local spin-valve devices

Abstract

We investigate spin and charge transport in both single and bilayer graphene non-local spin-valve devices. Similar to previous studies on bilayer graphene, we observe an inverse dependence of the spin lifetime on the carrier mobility in our single layer devices. This general trend is only observed in devices with large contact resistances. Furthermore, we observe a second Dirac peak in devices with long spin lifetimes. This results from charge transport underneath the contacts. In contrast, all devices with low ohmic contact resistances only exhibit a single Dirac peak. Additionally, the spin lifetime is significantly reduced indicating that an additional spin dephasing occurs underneath the electrodes.

5 pages, 3 figures

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• Determination of the spin-lifetime anisotropy in graphene using oblique spin precession
• Magnetotransport in heterostructures of transition metal dichalcogenides and graphene
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• Measuring anisotropic spin relaxation in graphene
• Observation of spin-charge conversion in CVD-grown single-layer graphene
• Spin field-effect transistor action via tunable polarization of the spin injection in a Co/MgO/graphene contact
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• Microscopic linear response theory of spin relaxation and relativistic transport phenomena in graphene
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• Simulations on the influence of spatially-varying spin transport parameters on the measured spin lifetime in graphene non-local spin valves
• Nanosecond spin lifetimes in bottom-up fabricated bilayer graphene spin-valves with atomic layer deposited Al${}_2$O${}_3$ spin injection and detection barriers
• Contact-less characterizations of encapsulated graphene p-n junctions
• A roadmap for the design of four-terminal spin valves and the extraction of spin diffusion length
• Room-temperature spin-lifetime anisotropy exceeding 60 in bilayer graphene spin valves proximity coupled to WSe${}_2$
• Enhanced Tunnel Spin Injection into Graphene using Chemical Vapor Deposited Hexagonal Boron Nitride