Abstract
The magnetic structure and magnetic transport properties of hydrogen-passivated sawtooth zigzag-edge graphene nanoribbons (STGNRs) are investigated theoretically. It is found that all-sized ground-state STGNRs are ferromagnetic and always feature magnetic semiconductor properties, whose spin splitting energy gap Eg changes periodically with the width of STGNRs. More importantly, for the STGNR based device, the dual spin-filtering effect with the perfect (100%) spin polarization and high-performance dual spin diode effect with a rectification ratio about 1010 can be predicted. Particularly, a highly effective spin-valve device is likely to be realized, which displays a giant magnetoresistace (MR) approaching 1010%, which is three orders magnitude higher than the value predicted based on the zigzag graphene nanoribbons and six orders magnitude higher than previously reported experimental values for the MgO tunnel junction. Our findings suggest that STGNRs might hold a significant promise for developing spintronic devices.
Highlights
The magnetic structure and magnetic transport properties of hydrogen-passivated sawtooth zigzag-edge graphene nanoribbons (STGNRs) are investigated theoretically
We construct device models by the STGNRs to investigate magnetic transport behaviors, where a device is divided into three regions: left electrode, right electrode, and the scattering region
Each electrode is represented by a unit cell of STGNR along the axis and descried by selfenergies, and the scattering region is involved in the self-consistent cycle for calculations and takes into account the interface coupling and screening layer effects
Summary
The magnetic structure and magnetic transport properties of hydrogen-passivated sawtooth zigzag-edge graphene nanoribbons (STGNRs) are investigated theoretically. Heretofore, many effective approaches, such as edge modifications[8], doping[9], introducing topologic defects[10], and applying an external electrical field[4] or magnetic field[5], have been proposed to break the spin degeneracy and stabilize ferromagnetic (FM) state in ZGNRs, achieving metallic or half- metallic features Based on these ways, some important phenomena are found and promising STDs, such as giant magnetoresistance devices and conductance switchers[5], spin-filtering devices[6], bipolar spin diodes[6,7], spin-polarized current amplifiers[7], and bipolar field-effect spin-filtering devices[11], are designed theoretically. Unique band overlap pattern for two electrodes and its particular sensitivity to a switching magnetic field lead to the dual spin-filtering effect with the perfect (100%) spin polarization and high-performance dual spin diode effect with a rectification ratio about 1010, as well as a highly effective spin-valve device feature with a giant magnetoresistace (GMR) value approaching 1010% can be observed
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