Tuning the tunneling magnetoresistance by using fluorinated graphene in graphene based magnetic junctions

Shweta Meena,Sudhanshu Choudhary

doi:10.1063/1.5009087

Shweta Meena, Sudhanshu Choudhary

Open Access

https://doi.org/10.1063/1.5009087

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Journal: AIP Advances	Publication Date: Dec 1, 2017
Citations: 9	License type: cc-by

Affiliation: National Institute of Technology Kurukshetra

Abstract

Spin polarized properties of fluorinated graphene as tunnel barrier with CrO2 as two HMF electrodes are studied using first principle methods based on density functional theory. Fluorinated graphene with different fluorine coverages is explored as tunnel barriers in magnetic tunnel junctions. Density functional computation for different fluorine coverages imply that with increase in fluorine coverages, there is increase in band gap (Eg) of graphene, Eg ∼ 3.466 e V was observed when graphene sheet is fluorine adsorbed on both-side with 100% coverage (CF). The results of CF graphene are compared with C4F (fluorination on one-side of graphene sheet with 25% coverage) and out-of-plane graphene based magnetic tunnel junctions. On comparison of the results it is observed that CF graphene based structure offers high TMR ∼100%, and the transport of carrier is through tunneling as there are no transmission states near Fermi level. This suggests that graphene sheet with both-side fluorination with 100% coverages acts as a perfect insulator and hence a better barrier to the carriers which is due to negligible spin down current (I↓) in both Parallel Configuration (PC) and Antiparallel Configuration (APC).

Highlights

Electron has a spin and a charge, but until now, charges and spins were considered distinctly
Choudhary to C4F graphene structure, possibly because of larger bandgap when graphene sheet is fluorinated on both sides with 100% coverage (CF)
In case of Antiparallel Configuration (APC), almost zero spin-up current I(↑) is observed and spin-down I(↓) current is negligible when graphene sheet is fluorinated on both sides with 100% (CF) coverage

Summary

Introduction

Electron has a spin and a charge, but until now, charges and spins were considered distinctly. Some of the traditional technologies, like magnetic tapes, use the spin of electron through the magnetization of a ferromagnet. This unfolded another way of efficiently controlling the movement of electrons by acting on their spin through the magnetic orientation of the ferromagnet. This stimulated the growth of a novel field of study called spintronics,[1] which exploits the spin movement of electron in ferromagnetic materials. Due to an assembly of interesting electronic properties,[16] graphene has enticed a great deal of attention and is an encouraging prospect as a building block in spintronics

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