NOKIA MEETING1 APS MARCH MEETING 2007 Denver, Colorado LATEST IN GRAPHENE RESEARCH Mikko Paalanen Low Temperature Laboratory Helsinki University of Technology
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)
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
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)
NOKIA MEETING5 THREE INTERESTING RESULTS Colombia University (Philip Kim et al) IBM Yorktown (Avouris et al) Leiden University (Carlo Beenakker et al)
NOKIA MEETING6 ENERGY BAND GAP ENGINEERING OF GRAPHENE NANORIBBONS arXiv:cond-mat/ Colombia, Philip Kim et al
NOKIA MEETING7 Dead edge of the order of 15 nm!
NOKIA MEETING8 Energy gap scales as 1/(w – w 0 ) No orientation dependence w min = 15 nm E gmax = 200 meV
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
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
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 .....
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?