Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.
-
Upload
gordon-arford -
Category
Documents
-
view
220 -
download
0
Transcript of Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.
![Page 1: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/1.jpg)
Gate Control of Spin Transport in Multilayer Graphene
By H. Goto et al.
Kun Xu
![Page 2: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/2.jpg)
AdvantagesAdvantages of spin over charge:
◦Easily manipulatable with externally applied magnetic fields
◦Long coherence/relaxation time
![Page 3: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/3.jpg)
GMR
Giant magnetoresistance◦Sandwich structure
FNF
◦Spin valve (HDD read/write heads)
◦The 2007 Nobel Prize in physics was awarded to Albert Fert and Peter Grünberg for the discovery of GMR
![Page 4: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/4.jpg)
Disadvantages
Existing spin devices do not amplify signals
![Page 5: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/5.jpg)
Datta-Das Device
Current modulated by the degrees of precession in electron spin introduced by the gate field
![Page 6: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/6.jpg)
Spin-based quantum Computer
Qubit – intrinsic binary unitsQuantum entanglementSingle electron trapped in a
quantum dot
![Page 7: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/7.jpg)
Spin transport in graphite based devicesCarbon nanotubesGrapheneMultilayer graphene (MLG)
Weak spin-orbit and hyperfine interaction
Gate control of spin conduction
![Page 8: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/8.jpg)
![Page 9: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/9.jpg)
Device StructureMLG Exfoliated from kish
graphite2.5nm thick, about 7 layers (by
SEM/AFM)Doped Si/SiO2 substrate
![Page 10: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/10.jpg)
Device Structure50nm Co electrodes
200nm/330nmSeparated by L=290nm
![Page 11: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/11.jpg)
Device StructureCr/Au nonmagnetic electrodes5nm/100nm thick
![Page 12: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/12.jpg)
MeasurementFour terminal lock-in technique4.2KExcitation current of 1.0 uA,
119HzBack gate bias
![Page 13: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/13.jpg)
Spin Signal: Rs
Rs=Rp-Rap
Proportional to Rwhen FN interfaces are
opaqueProportional to 1/R
when FN interfaces are transparent
![Page 14: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/14.jpg)
Spin Signal: Rs
![Page 15: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/15.jpg)
Spin Signal: Rs
Vn=1.5V
![Page 16: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/16.jpg)
Spin relaxation length
![Page 17: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/17.jpg)
Spin relaxation lengthMLG
Graphene: 1.5-2 um at room temperaure, may stay the same at low temperature
![Page 18: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/18.jpg)
?
![Page 19: Gate Control of Spin Transport in Multilayer Graphene By H. Goto et al. Kun Xu.](https://reader031.fdocuments.in/reader031/viewer/2022020800/5519b93c5503467a578b4905/html5/thumbnails/19.jpg)