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Abstract: Electronic transport in a graphene-based ferromagnetic-normal-ferromagneticjunction is investigated by means of Landauer-B\-{u}ttiker formulism and thenonequilibrium Green-s function technique. For the zigzag edge case, theresults show that the conductance is always larger than $e^{2}-h$ for theparallel configuration of lead magnetizations, but for the antiparallelconfiguration the conductance becomes zero because of the band-selective rule.So a magnetoresistance MR plateau emerges with the value 100% when the Fermienergy is located around the Dirac point. Besides, choosing narrower grapheneribbons can obtain the wider 100% MR plateaus and the length change of thecentral graphene region does not affect the 100% MR plateaus. Although thedisorder will reduce the MR plateau, the plateau value can be still kept about50% even in a large disorder strength case. In addition, when themagnetizations of the left and right leads have a relative angle, theconductance changes as a cosine function of the angle. What is more, for thearmchair edge case, the MR is usually small. So, it is more favorable tofabricate the graphene-based spin valve device by using the zigzag edgegraphene ribbon.



Author: Jiang-chai Chen, Shu-guang Cheng, Shun-Qing Shen, Qing-feng Sun

Source: https://arxiv.org/







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