Room-Temperature Spin Filtering in Metallic Ferromagnet-Multilayer Graphene-Ferromagnet Junctions.
We report room-temperature negative magnetoresistance in ferromagnet-graphene-ferromagnet (FM|Gr|FM) junctions with minority spin polarization exceeding 80%, consistent with predictions of strong minority spin filtering. We fabricated arrays of such junctions via chemical vapor deposition of multilayer graphene on lattice-matched single-crystal NiFe(111) films and standard photolithographic patterning and etching techniques. The junctions exhibit metallic transport behavior, low resistance, and the negative magnetoresistance characteristic of a minority spin filter interface throughout the temperature range 10 to 300 K. We develop a device model to incorporate the predicted spin filtering by explicitly treating a metallic minority spin channel with spin current conversion and a tunnel barrier majority spin channel and extract spin polarization of at least 80% in the graphene layer in our structures. The junctions also show antiferromagnetic coupling, consistent with several recent predictions. The methods and findings are relevant to fast-readout low-power magnetic random access memory technology, spin logic devices, and low-power magnetic field sensors.
Naval Research Laboratory , 4555 Overlook Avenue SW, Washington D.C. 20375, United States.
Enrique D
ED
Cobas
Naval Research Laboratory , 4555 Overlook Avenue SW, Washington D.C. 20375, United States.
Olaf M J
OM
van 't Erve
Naval Research Laboratory , 4555 Overlook Avenue SW, Washington D.C. 20375, United States.
Shu-Fan
SF
Cheng
Naval Research Laboratory , 4555 Overlook Avenue SW, Washington D.C. 20375, United States.
James C
JC
Culbertson
Naval Research Laboratory , 4555 Overlook Avenue SW, Washington D.C. 20375, United States.
Glenn G
GG
Jernigan
Naval Research Laboratory , 4555 Overlook Avenue SW, Washington D.C. 20375, United States.
Konrad
K
Bussman
Naval Research Laboratory , 4555 Overlook Avenue SW, Washington D.C. 20375, United States.
Berend T
BT
Jonker
graphene; magnetoresistance; spin filtering