Probing Tunneling Spin Injection into Graphene via Bias Dependence

Abstract

The bias dependence of spin injection in graphene lateral spin valves is systematically studied to determine the factors affecting the tunneling spin injection efficiency. Three types of junctions are investigated, including MgO and hexagonal boron nitride (hBN) tunnel barriers and direct contacts. A DC bias current applied to the injector electrode induces a strong nonlinear bias dependence of the nonlocal spin signal for both MgO and hBN tunnel barriers. Furthermore, this signal reverses its sign at a negative DC bias for both kinds of tunnel barriers. The analysis of the bias dependence for injector electrodes with a wide range of contact resistances suggests that the sign reversal correlates with bias voltage rather than current. We consider different mechanisms for nonlinear bias dependence and conclude that the energy-dependent spin-polarized electronic structure of the ferromagnetic electrodes, rather than the electrical field-induced spin drift effect or spin filtering effect of the tunnel barrier, is the most likely explanation of the experimental observations.

10 pages, 6 figures

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Cited by in corpus (9)

• Spin inversion in graphene spin valves by gate-tunable magnetic proximity effect at one-dimensional contacts
• Spin field-effect transistor action via tunable polarization of the spin injection in a Co/MgO/graphene contact
• Van der Waals Magnetic Electrode Transfer for Two-Dimensional Spintronic Devices
• Efficient spin injection into graphene through trilayer hBN tunnel barriers
• Charge-induced artifacts in non-local spin transport measurements: How to prevent spurious voltage signals
• Bias dependent spin injection into graphene on YIG through bilayer hBN tunnel barriers
• Nonlinear analog spintronics with van der Waals heterostructures
• Proximity-induced magnetization in graphene: Towards efficient spin gating
• Room-temperature spin-lifetime anisotropy exceeding 60 in bilayer graphene spin valves proximity coupled to WSe${}_2$