11

Andre Geim (1958) is a Russian-born Dutch physicist,currently director of the Manchester Centre forMesoscience and Nanotechnology at the ManchesterUniversity, known for the discovery of graphene, thedevelopment of gecko tape and demonstrations ofdiamagnetic levitation.

Konstantin Sergeevich Novoselov (1974) is a Russian-British physicist, currently Professor at the University ofManchester, known for his work on mesoscopicsuperconductivity , Sub-atomic movements of magneticdomain walls, the invention of graphene.

Nobel prize in physics 2010

Recent progress on graphene

Reza Asgariasgari@ipm.ir

11The annual spring conference , IPM 19-20 May 2011

33

1. Introductionbrief overview ( Experimental & Theoretical views)

2. New resultsStrain ( engineering) in grapheneOptical propertiesElectron-electron interaction

3. ConclusionSpecial characteristic…..Open problems

Outlook

44

Graphite and Pencil

:روش ساخت Micromechanical cleavage

Epitaxy, requires ultrahigh vacuum conditions: Expensive Science 312, 1192 (2006)Various chemical methods. Nano Lett. 8, 2442 (2008) , Nature Nanotech. 3, 270 (2008);ibid 4,217(2009)Chemical Vapour Deposition : Nature 457, 706 (2009), Nano Lett. 9, 30 (2009)

Geim’s group: Science 306, 666 (2004) , Nature 438, 197(2005)

55

66

Graphene preparations

A. Geim Science 324, 1530(2009)

77

Graphene preparations

Keun Soo Kim, et al, Nature 457, 706(2009)

88

New preparations

Sukang Bae, et al, Nature nanotechnology 5, 574(2010)

99

Graphene as a Touch-Screen

1010

Samsung @ SKKU project

Flexible display in a large scale graphene based material

1111

Basic concepts in graphene

• Flatness, one atom thickness• Crystal structure• Dispersion relation• Chirality

Graphene has twoatoms per unit cell.

These two atoms fortwo interlockingtriangular sub-lattices.

- A atom

- B atom

1212

Graphene, a honeycomb lattice

Flat monolayer: roughness, ripples, wrinkles?

1313A. Geim Science 324, 1530(2009)

dispersion relations & chirality

1414

“Imagine a piece of paper but a million times thinner. This ishow thick graphene is.

Imagine a material stronger than diamond. This is how stronggraphene is [in the plane].

Imagine a material more conducting than copper. This is howconductive graphene is.

concerns new physics, no one doubts about it already...‘‘ …..

What graphene is?

nm *

qE

Novoselov, et al., Nature 438,197 (2005)

nq

Dirac massless: evidence

1515

1616

How do we determine the Fermi surface?

Angle-resolved photoemissionspectroscopy (ARPES)

1717

Some applications

• Klein tunneling• Transistors• Thermal conductivity• High mobility• Quantum dots• Strain engineering•Tunable gap in bilayer• Photonic and Solar cell• …..

1818

Observation of Klein tunneling

Williams, Di Carlo and Marcus, Science 317, 638(2007)

Satnder, Huard and Goldhaber-Gordon, Phys. Rev. Lett. 102, 026807 (2009)

1919Lin et al., Science. 327, 662 (2010)

100-GHz Transistors

2020Liao, et al., Nature In press (2010)

High-speed graphene transistors

2121

Graphene spreads the heat

Suspended SLGSupported SLG by Sio2Bulk copperThin film copper

1 13000 5000 Wm k 1 1600 Wm k

1 1400 Wm k

1 1250 Wm k

Seol, et al., Science 328, 213(2010)

At room temperature :

2222

Quantum dots in graphene as a basic forelectronic devices

Ponomarenko, et al., Science 320, 356 (2008)

2323

Strain Enginnering

Elasticity Theory Quantum mechanics

2424

1t

2t3t

ij jiij batH

Deformed graphene lattice

02 uua

ttt ijijij

)()(0 ruuu ijij

2525

IVeAPvH F )(

Graphene is distorted, the effective Hamiltonian will be changed into

Effective Hamiltonian

H. Suzuura and T. Ando, Phys. Rev. B 65, 235412 (2002)J. L. Manes, Phys. Rev. B 76, 045430 (2007)

VveAPeAPVv

vPHF

FF 1

**1

)(

VveAPeApVv

vpHF

FF 1**

1

)(

yx iAAA

2626

Induced vector potential field is defined through the deformations of sample

Strains:

0.56

K.V. Zakharchenko, M.I. Katsnelson, and A. Fasolino, Phys. Rev. Lett. 102, 046808 (2009)Y. C. Cheng, Z. Y. Zhu, G. S. Huang, and U. Schwingenschlögl, Phys. Rev. B 83, 115449 (2011)

Strains

2)()( aLogtLog

hhuuu 2

xyyF

yyxxxF

utAev

uutAev

23

)(4

3

2727

Elasticity theory

Pseudo-magnetic field

Deformed lattice

Ideas

2828

Effective Hamiltonian

F. Guinea, B. Horovitz and P. Le Doussal, Phys. Rev. B 77,205421(2008)E. V. Castro, et al. Phys. Rev. Lett. 105, 266601 (2010).Tony Low and F. Guinea, Nano Lett. 10, 3551 (2010).Vitor M. Pereira and A. H. Castro Neto, Phys. Rev. Lett. 103, 046801 (2009)

2929

Experiment

Leavy et al. Science 329, 554 (2010)

3030

Exp vs Theory

Leavy et al. Science 329, 554 (2010)

3131

Numerical Results vs Experiment data

N. Abedpour, R. A., F. Guinea , to be submitted

3232

Graphene ring: analytical solutions

Landau and Lifshitz, Theory of Elasticity, (Harvard)

0),( rh

0),(),(

0),(),( 11

RuURu

RuRu

r

r

21

221

2

21

)(),(

0),(

RRrR

RRrRRUru

rur

N. Abedpour, R. A., F. Guinea , submitted

3333

Analytical solutions: Pseudo-magnetic field

TnmRB 10)19,10( 01

example:

3

214

1 1056.0),,(rRRrB

)3cos()(

34),( 21

23

21

0

RRrRRU

arB

eh20

3434

Numerical results

)3cos(),( rBN. Abedpour, R. A., F. Guinea , submitted

3535

Co-exist CQHE with TRI ?

A. Vaezi, N. Abedpour, R. A., To be submitted

3636

Optical transmission propeties

Nearly perfect transparent

3737

Transmission of SLG/SiO2/Si

C. Lee et al., Appl. Phys. Lett. 98, 071905 (2011)

3838

Many-body effects

Are the many-body electron- electron interactionsessential for graphene?

X. Du, I. Skachko, F. Duerr, A. Luican, and E.Y. Andrei, Nature 462, 192 (2009)

K.I. Bolotin, F. Ghahari, M.D. Shulman, H.L. Stormer, and P. Kim, Nature462, 196 (2009)

Fractional quantum Hall effect

Interaction effects in STM

V.W. Brar et al., Phys. Rev. Lett. 104, 036805 (2010)

4141

ARPES: Gapless graphene

M. Polini, R. Asgari, G. Borghi, Y. Barlas, T. Pereg-Barnea, and A.H. MacDonald, Phys. Rev. B 77,081411(R) (2008)

4242

A. Qaiumzadeh and R. Asgari,New J. Physics, 11, 095023 (2009)

ARPES: gap opening

The plasmaron peak is suppressed

4343

Our recent work Science 328,999(2010)

4444

Dispersion relation (experiment)

4545Non-interacting,single-particle picture

Interacting,many-particles picture

My purpose

4646

Graphene on Metal

A. Principi, R. A, M. Polini, Submitted

4747

Phase diagram

A. Principi, R. A, M. Polini, Submitted

4848

Soundaron

A. Principi, R. A, M. Polini, Submitted

4949

Conclusion

1. Composite “ Plasmaron “ particles were observed.2. A quantitative agreement between experimental measurements

and theoretical model is satisfied.3. Dirac crossing is resolved into three crossing.4. Plasmaron properties can be used in photonic and electronic devices.

5050

Open problems

1. Quantum update ( see: San-Jose, Gonzalez and Guinea, arXiv:1009.1285)2. Chemical properties3. Transport properties near to the Dirac point4. More applications in PHOTONIC and SOLAR CELL5. Electronic properties ( the impact of e-e and e-ph interactions)6. Gas Sensors7. Nonlinear mechanical properties

5151

Allan MacDonald

Marco Polini

Eli RotenbergAaron BostwickThomas SeyllerKaron Horn

Experimentalists

Theorists

In collaborations with

Floran Speck

NimaAlireza

Khadijeh

reza

Ayub

Paco Guinea

H Cheraghchi

Ali Naji

H Vaezi

Thanks for your attention

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