Dvojrozmerne materialy:

ako lepiaca paska sposobila revoluciu

vo fyzike

Jaroslav Fabian

University of Regensburg

Veda v Centre, Bratislava 28.5.2015

Regensburg, Bayern

Universitt Regensburg

Arbeitsgruppe Prof. Fabian

Grafen:

od lepiacej pasky k

relativistickej fyzike

Grafen

Grafit (tuha)

Historia tuhy

1564 objavene lozisko v Borrowdale, Anglicko (cierne olovo, plumbago)

1779 chemik Carl W Scheele: je to forma uhlika

1789 geolog Abraham G. Werner: volajme to grafit, grecky graphein ()

= pisat

1795 chemik Nicolas-Jacques Cont: zmiesajme grafit, il (clay), a vodu = tuha

Uhlikova ZOO

? diamond

graphite

Carbon nanotube

Buckyball, C60

Nobel Prize in Chemistry 1996

Curl, Kroto, Smalley

Is there more?

Ako spravi objav easy way (a dosta Nobelovu cenu)

SiO2 substrate

Scotch tape

Tesa

graphite

Grafenovska revolucia

Nobel Prize 2010

Andre Geim Konstantin Novoselov

Mozu vobec 2-rozmerne materialy

existovat? Peirls, R.E, Bemerkungen ber Umwandlungs

temperature, Helv. Phys. Acta 7, 81-83 (1934).

Landau,L.D and Lifshitz, Statistical Physics (Pergamon, Oxford 1980).

Nekonecny 2-rozmerny krystal nemoze existovat v trojrozmernom

svete pri nenulovej teplote

Ale:

konecny krystal

substrat

zvlnenie (rippling)

Grafen na substrate

1.4

atomy uhlika

baza

Ako tenky je grafen?

1 = 0.000 000 000 1 m = 0.000 000 1 mm

Ako tenky je papier?

5 cm, 500 ks 5 cm : 500 = 0.1 mm

Ako tenky je grafen?

grafen = 0.000 000 1 mm

papier = 0.1 mm = 1 000 000 grafenov

papier grafenove

listy

Ako tenka je stopa ceruzky?

Ako tenka je stopa ceruzky?

priemerna ceruzka spravi ciaru 60 km

meranie courtesy

Ing. Slavomir Fabian

6e

2s2 1s2 2p2

elektronovy svet grafenu

atom uhlika

vazby

pevnost: 3 elektrony na atom

elektricke, opticke, spinove

vlastnosti

elektronovy oblak: 1 elektron na atom

Jemna relativita

= +

,

= +

=

=

Normalna castica Castica s nulovou hmotnostou

hybnost rychlost svetla 300 mil m/s

Jemna kvantova mechanika

= 2

elektron

gulicka

vlna

De Broglie

Schrdinger

Normalne vodice

energia

1

4

hybnost

1

2

elektron-vlna

Normalne vodice

kov

polovodic

Energeticka medzera

Grafene: exoticky vodic

Polokov

Dirakove spektrum,

Elektrony bez hmotnosti, neutrina

rychlost:

v = 1 000 000 m/s = c/300

energia

1

2

Skumame grafen:

elektricke a magneticke pole,

svetlo, deformacia

Napatie na hradle

Kims group Nature 438, 201-204 (2005)

Skumame grafen:

el. polom riadena vodivost

Kims group Nature 438, 201-204 (2005)

~ || ~ ( +0.5)

Skumame grafen:

magneticke pole

Normalny vodic Grafen

skenovaci tunelovaci mikroskop

(STM) Okno do sveta atomov

Courtesy Tobias Frank

N. Levy et al. Science 2010;329:544-547

Skumame grafen: Deformacia vytvara magneticke pole

nanobubliny

Efektivne

magneticke pole

300 Tesla!!!

Nair at al, Science, 320 (2008)

Kvantova elektrodynamika v grafene

=

= /

Feynman: You might say the "hand of God" wrote that number, and "we

don't know how He pushed his pencil."

JF: He pushed it such as to create graphene!

= . %

Absorpcia svetla

grafenom

Graphene highlights

hustota 0.77 mg/m2

opticka priesvitnost 97,7% vysoka mobilita pri izbovej teplote

vodivost ovladana polom

100 krat silnejsi ako ocel

tepelna vodivost 10 krat lepsia ako medi

uplna nepriepustnost voci plynom

vlastnosti menitelne povrchovymi primesmi

netoxicky, vo vode nerozpustny

moznost vyroby velkych ploch (1 meter)

CVD: chemicke naparovanie

http://www.science.oregonstate.edu/~minote/wiki

Dvojrozmerne materialove ZOO:

Ucime sa kvantovu mechaniku v 2

rozmeroch

graphene germanene,

silicene MoS2 NbSe2

hBN

phosphorene

supravodic

polovodic dielektrikum polokov

Spintronika

Elektrony maju spin: tocia sa

Pauli Bohr

The spintronics revolution

Nobel Prize 2007

Albert Fert Peter Grnberg

small resistance large resistance

10 nm

1947 Nobel Prize in Physics 1956

Bardeen, Brattain, Shockley

The transistor revolution

Ked sa zapnu relativisticke korekcie,

elektrony v grafene ziskaju (malu) hmotnost

Injekcia spinu do grafenu van Wees group,

Electronic spin transport and spin precession in single graphene layers at room temperature,

Nature 448, 571 (2007)

Zahada ultrarychlej spinovej relaxacie v grafene

Pre porovnanie: kremik ma spin-relaxacny cas 10 ns

Zname mechanizmy davaju mikrosekundy !!!

Co maju spolocne adatomy v

grafene a RH120?

orbity

minimesiac

Adatomy v grafene su ako zem,

a elektrony ako minimesiace: orbituju okolo a stracaju spin

Courtesy Martin Gmitra

Resonant spin-flip scattering by local moments

puddles

D. Kochan, M. Gmitra, and J. Fabian, PRL 112, 116602 (2014)

Dekorovany (funkcionalizovany)

grafen

, , ,

Courtesy Martin Gmitra

Najtensi feromagnet?

Courtesy Martin Gmitra

Materialove Lego

Courtesy Martin Gmitra

optospintronics:

graphene on TMC

Courtesy of Martin Gmitra

Graphene Flagship

> 100 EU partners

EU funding 10 years

1 Miliarda euro

Applications

Odsolovanie morskej vody

Mathematics is the language with

which God wrote the Universe

A pisal to grafenovou ceruzkou

(And He wrote it with graphene pencil)

JF