About OMICS Group OMICS Group International is an amalgamation of Open Access publications  - PowerPoint Presentation

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About OMICS Group

OMICS Group International is an amalgamation of Open Access publications and worldwide international science conferences and events. Established in the year 2007 with the sole aim of making the information on Sciences and technology ‘Open Access’, OMICS Group publishes 400 online open access scholarly journals in all aspects of Science, Engineering, Management and Technology journals. OMICS Group has been instrumental in taking the knowledge on Science & technology to the doorsteps of ordinary men and women. Research Scholars, Students, Libraries, Educational Institutions, Research centers and the industry are main stakeholders that benefitted greatly from this knowledge dissemination. OMICS Group also organizes 300 International conferences annually across the globe, where knowledge transfer takes place through debates, round table discussions, poster presentations, workshops, symposia and exhibitions

.

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About OMICS Group Conferences

OMICS Group International is a pioneer and leading science event organizer, which publishes around 400 open access journals and conducts over 300 Medical, Clinical, Engineering, Life Sciences,

Phrama

 scientific conferences all over the globe annually with the support of more than 1000 scientific associations and 30,000 editorial board members and 3.5 million followers to its credit.

OMICS Group has organized 500 conferences, workshops and national symposiums across the major cities including San Francisco, Las Vegas, San Antonio, Omaha, Orlando, Raleigh, Santa Clara, Chicago, Philadelphia, Baltimore, United Kingdom, Valencia, Dubai, Beijing, Hyderabad,

Bengaluru

and Mumbai.

Slide3

Materials Science-2014

　

Oct. 6. 2014

Toho Univ., N. Tajima

Quantum

Hall

effect in multilayered massless Dirac fermion systems

Quantum transport phenomena

carriers (holes)

doping

SdH

& QHE

a

-(

BEDT-TTF)2I3 (p>1.5 GPa)

Dirac fermion system

Slide4

Toho Univ.

:T. Ozawa, T.

Y

amauchi, Y.

Nishio

and K.

KajitaRIKEN :Y. Kawasugi and R. KatoIMS :M. Suda and H. M. Yamamoto

Slide5

Outline

1. Introduction

2

.

holes-doping:

SdH

and QHE

3. Conclusions

Slide6

Outline

1. Introduction

2

.

holes-doping:

SdH

and QHE

3. Conclusions

Slide7

a

-(BEDT-TTF)

2

I

3

(p>1.5GPa)Katayama, et al.,

Graphene: monolayer of graphiteK. S. Novoselov et al., Nature 438(2005)197. Y. Zhang et al., Nature 438(2005)201.

P.R. Wallace,

Phys. Rev. 71, 622 (1947)

graphite

First bulk zero-gap material

1.

Introduction

：　

a

-(BEDT-TTF)

2

I

3

Slide8

a

b

c

o

K.Bender, et al., Mol. Cryst. liq. Cryst., 108 (1984) 359

[

2

]

(+)

I

3

(-)

e

BEDT-TTF

2D-system

Insulating layer (I

3

)

Conductive layer (BEDT-TTF)

Insulating layer (I

3

)

Conductive layer (BEDT-TTF)

Conductive layer (BEDT-TTF)

1.

Introduction

：　

a

-(BEDT-TTF)

2

I

3

Slide9

+1

e

0

+0.5

e

+0.5

e

a

b

a

b

o

o

T

< 135K

T >

135K

Charge disproportionation

H.Kino

and

H.Fukuyama

(Theory)

J. Phys. Soc.

Jpn

. 64(1995)1877.

Y.Takano

, et.al. (NMR)

J. Physics and Chemistry. Solid 62(2001) 393.

H.Seo

(Theory)

J

. Phys. Soc.

Jpn

. 69(2000)805.

R.Wojciechowski

, et.al. (Raman)

Phys.Rev.B

67(2003) 224105.

135K

1.

Introduction

：　

a

-(BEDT-TTF)

2

I

3

Slide10

Sample

Teflon

Pressure medium: Oil

※

1kbar=0.1GPa=

10,000

atm

Zero-gap system: Dirac fermion

1.

Introduction

：　

a

-(BEDT-TTF)

2

I

3

Slide11

What is interesting?

Dirac cone

Dirac point

(contact point)

m

*=0

: massless Dirac electrons

(relativistic electrons)What is important?

:normal-

e

 

 

 

1.

Introduction

：　

a

-(BEDT-TTF)

2

I

3

Slide12

1.

Introduction

：

Characteristic transport

Sheet resistance:

 

Carrier density:

 

Anomalous

due to inter-band effects of

B

 

peculiar

magnetotransport

・

Toho Univ. & RIKEN

・

Toho Univ. & RIKEN

・

Toho Univ. & RIKEN

・

A. Kobayashi, et al

・

Toho Univ. & RIKEN

Slide13

Conventional conductor

Zero-gap structure

B

B

 

 

1.

Introduction

：　

Landau level

Slide14

3)

s

zz

∝

n

0LL

∝B1) E1LL»kB

T,  quantum limit

r

zz

B

2) Degeneracy of zero mode

　　：

n

0LL

(

B

) =

B

/2

f

0

,

f

0

=

h

/

e

r

zz

∝

1/

B

N. T, et al., PRL, 102, 176403 (2009).

Osada

formula

(T.

Osada

, JPSJ 77 (2008) 084711)

1.

Introduction

：　

Zero-mode

Slide15

Outline

1. Introduction

2

.

holes-doping:

SdH

and QHE

3. Conclusions

Slide16

DOS

E

B

=0

B

DOS

E

B

=0

B

DOS

E

B

=0

B

E

F

E

F

E

F

Undoped

state

e

h

B

=0

Can we inject the carriers into the sample?

2. holes-doping

：　

Other Landau level

Slide17

DOS

E

B

=0

B

DOS

E

B

=0

B

DOS

E

B

=0

B

E

F

E

F

E

F

Undoped

state

e

h

B

=0

2. holes-doping

：

Yes



Breakthrough

Can we inject the carriers into the sample?

Slide18

1. PEN is slightly charged in negative.

2.

at low-

T

 

 

Fermi-liquid sate

2. holes-doping: resistivity

N. T, et al.,

PRB, 88, 075315 (2013).

Slide19

1. PEN is slightly charged in negative.

2.

at low-

T

 

hole-doping

2. holes-doping:

SdH

& QHE

N. T, et al.,

PRB, 88, 075315 (2013).

Slide20

3. Results

：　

SdH

& QHE

 

:

normal -

e

 

:

Dirac -

e

 

Energy diagram

 

N. T, et al.,

PRB, 88, 075315 (2013).

Slide21

 

 

 

QHE in 2D Dirac system

2. holes-doping

N. T, et al.,

PRB, 88, 075315 (2013).

Slide22

 

2. holes-doping: QHE at 5.5 T

N. T, et al.,

PRB, 88, 075315 (2013).

Slide23

Thickness dependence of conductivity

At

 

✔

QHE around 5.5 T

 

✔

Undoped layer

2. holes-doping: QHE at 5.5 T

N. T, et al.,

PRB, 88, 075315 (2013).

Slide24

Crystals on PEN

Direct

evidence of Dirac system

First

observation of

SdH

& QHE

holes dopingFermi liquid state

3. Conclusions

Slide25

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