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20.4. 2007NOKIA MEETING1 APS MARCH MEETING 2007 Denver, Colorado 5.3.-9.3. 2007 LATEST IN GRAPHENE RESEARCH Mikko Paalanen Low Temperature Laboratory Helsinki.

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Presentation on theme: "20.4. 2007NOKIA MEETING1 APS MARCH MEETING 2007 Denver, Colorado 5.3.-9.3. 2007 LATEST IN GRAPHENE RESEARCH Mikko Paalanen Low Temperature Laboratory Helsinki."— Presentation transcript:

1 NOKIA MEETING1 APS MARCH MEETING 2007 Denver, Colorado LATEST IN GRAPHENE RESEARCH Mikko Paalanen Low Temperature Laboratory Helsinki University of Technology

2 NOKIA MEETING2 APS MARCH MEETING 2007 STATISTICS  SCIENTIFIC SESSIONS  Total 520  Graphene sessions 7 + a tutorial session  Carbon nanotube sessions 14  INVITED TALKS  Total 720  Graphene talks 10 (6 E, 4 T)  Carbon nanotube talks 11 (8 E, 3 T)

3 NOKIA MEETING3 STATISTICS  Contributed talks about graphene  Total66  Theory talks37  Experimental  Electron transport14  Mechanical properties 9  Microscopy 6 29  More experiments needed, theory is advancing fast

4 NOKIA MEETING4 COMPETITORS ON EXPERIMENTAL SIDE  Univ. of Manchester (Andrei Geim et al since 2004)  Georgia Tech (Walter DeHeer et al)  Colombia University (Philip Kim et al)  Rutgers University (Eva Andrei et al)  IBM Yorktown (Avouris et al)  Cornell University (Paul McEuen et al)

5 NOKIA MEETING5 THREE INTERESTING RESULTS  Colombia University (Philip Kim et al)  IBM Yorktown (Avouris et al)  Leiden University (Carlo Beenakker et al)

6 NOKIA MEETING6 ENERGY BAND GAP ENGINEERING OF GRAPHENE NANORIBBONS arXiv:cond-mat/ Colombia, Philip Kim et al

7 NOKIA MEETING7 Dead edge of the order of 15 nm!

8 NOKIA MEETING8 Energy gap scales as 1/(w – w 0 ) No orientation dependence w min = 15 nm E gmax = 200 meV

9 NOKIA MEETING9 IBM, AVOURIS et al arXiv:cond-mat/ arXiv:cond-mat/ /f noise similar to CNT Due to resistance fluctuations w min = 20 nm E gmax = 30 meV

10 NOKIA MEETING10 SNS-JUNCTION IN GRAPHENE Leiden University, Carlo Beenakker arXiv:cond-mat/ Supercurrent creates a transverse spin and thermal currents Thermal current depends on phase difference

11 NOKIA MEETING11 WHY GRAPHENE WHY NOT CARBON NANOTUBES  High electron mobility even at room temperature  Long mean free path, electron backscattering weak  Long coherence length (dephasing due to e-e collisions)  Contacts easier to make than for nanotubes  Can be fabricated lithographically as large wafers (SiC)  Metallic interconnects may not be needed  Promise for new type of electronics  Electron wave guide electronics  Terahertz detectrors .....

12 NOKIA MEETING12 INTERESTING QUESTIONS  How do electronic properties depend on substrate?  Free standing sheet versus SiC  Multilayered graphene  Interphase states and doping  What about narrow wires and quantum dots?  Rough edges seem to play a role?  How to prepare smooth edges?  Tuning of the gap in narrow wires?


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