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Sinn für Drehungen im Nanokosmos

Stefan Blügel

IFF-I, Institut für Festkörperforschung

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www.fz-juelich.de/iff/e_th1Marilyn Monroe

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Encore Celebrity Images

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www.fz-juelich.de/iff/e_th1Marilyn Monroe

Andy Warhol

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www.fz-juelich.de/iff/e_th1Reminder : Chirality

An object that cannot be superimposed on its mirror image

mirror

Chiral objectsNonsuperimposablemirror images

mirror

Nonchiral objectssuperimposablemirror images

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www.fz-juelich.de/iff/e_th1Chirale Moleküle

Bad Neuenahr June -2007

www.fz-juelich.de/iff/e_th1Chirale Moleküle

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Reminder : Parity violation

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Parity principle: Right and left handed versions of chiral objects or processes should exist with equal probability

• Electro-weak interaction SU(2)L

• Parity violation in terrestrial Biopolymers: DNA

Exceptions:

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Drehimpuls L = m (v x r)

t -t v -v L -L

Time-inversion symmetry (1)

Rechtsdrehung vorwärts Rechtsdrehung rückwärts

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L

r

v

t -t v -v L -L

t -t

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Time-inversion symmetry (2)

Rechtsdrehung rückwärtsLinksdrehung vorwärts

Der zeitumgekehrte Prozess lässt sich physikalisch realisieren!

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Spatial inversion (parity)

Der spiegelbildliche Prozess (hier ebenfalls die umgekehrte Drehung) ist ebenfalls physikalisch realisierbar.

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Inversion hier veranschaulicht an hand der ähnlichen Spiegelung

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www.fz-juelich.de/iff/e_th1Helizität des Lichts

Die Intensität des Lichts bestimmtdie Anzahl der Photonen, die wie Teilchen agieren

Lichtgeschwindigkeit

50% aller Photonenhaben Chiralität= -1

50% aller Photonenhaben Chiralität= +1

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Der Photoelektrische Effekt

Metalloberfläche

Die Intensität des Lichts bestimmtdie Anzahl der Elektronen

50% aller Elektronenhaben Chiralität=-1/2 50% aller Elektronenhaben Chiralität= +1/2

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Spiral Galaxies

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Parity Violation at Surfaces

time inversion

Tmirror reflection

R

time inversion

Tmirror reflection

R

time inversion

T

E =E(TR)

E =E(TR)

E ≠E(TR)

mirror reflection

R

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www.fz-juelich.de/iff/e_th1Homochiral Magnetic State

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Consequences of symmetry breaking

|L> |R>

FM/AFM

E(c)

c

For magnetic nanostructure it holds that:If chirality can be broken, spin-orbit interaction will break it!

After 25 years of surface magnetism, is this of relevance oris it smoke of theory?

o Does ferro- or antiferromagnetism exists at surfaces at all ?o For domain walls, chirality can be broken i.e. there should be only walls of one type

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www.fz-juelich.de/iff/e_th1Complete Picture

HeisenbergExchange

DzyaloshinskiiMoriya-Exchange

Magneto-CrystallineAnisotropy

Dipol-DipolAnisotropy

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www.fz-juelich.de/iff/e_th1Phase Diagramme

M. Heide, G. Bihlmayer and S. Blügel

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Model system: Monolayer Mn on W(110)

0.75 ML

+ 10

0 m

eV/A

tom

+ 10

0 m

eV/A

tom

± 0

meV

/Ato

m±

0 m

eV/A

tom

+ 70

meV

/Ato

m+

70 m

eV/A

tom

Magnetic Configuration: Pseudomorphic Growth:

M. Bode et al., Surf. Sci. 432, 8 (1999).

Cu-Atome

Vakuum

Mn-Atome

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www.fz-juelich.de/iff/e_th1Imaging Mn/W(110)

Non-magnetic W-TipNon-magnetic W-Tip

S. Heinze, M. Bode et al.,

Science 288, 1805 (2000).

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Quantum Mechanics of Electrons: Many-body problem

iron atom:

26 electron wave-function: Ψ(r1,...r26)

store only 10 values per coordinate: 1078 values

assume each value could be stored

in a single H atom: memory heavier than the milky way

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Density Functional Theory (DFT)

Total Energy:

Secular Equation:

Density:

Energy is functional of electron density n and external parameterssuch as lattice constants, atoms positions, magnetization direction…

CPU time proportional to N3:

Selfconsistency loop

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The Nobel Prize in Chemistry 1998

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"for his development of the density-functional theory"

"for his development of computational methods in quantum chemistry"

Walter Kohn John A. Pople

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Revolution in Computing Power:

cutting supercomputing in nanomagnetism

A. E. Brenner, Physics Today, October 1996

$1K

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Imaging the Magnetic Ground State of 1ML-Mn/W(110)Non-magnetic W-TipNon-magnetic W-Tip Magnetic Fe-TipMagnetic Fe-Tip

First experimental Proof of the 2D-AFM!First experimental Proof of the 2D-AFM!S.Heinze, M. Bode, A. Kubetzka, X. Nie, O. Pietsch, S.Blügel, Wiesendanger, Science 288 (2000)

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Revolution in Computing Power:

cutting supercomputing in nanomagnetism

A. E. Brenner, Physics Today, October 1996

$1K

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New Interaction discovered

Bode, Heide, von Bergmann, Ferriani, Heinze, Bihlmayer, Kubetzka, Pietzsch, Blügel, Wiesendanger,

cycloidal spiral

x

Nature 447, 190 (2007)

|L> |R>

FM/AFM

E(c)

c

JUMP

λ =8nm =40atoms

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www.fz-juelich.de/iff/e_th1Tool-driven revolutions

Dyson, F., Imagined Worlds, Harvard University Press, Cambridge, MA, 1997, pgs. 50-51.

New directions in science are launched by new tools more often than by new scientific concepts.

The effect of a concept-driven revolution is to explainold things in new ways. The effect of a tool-driven re-volution is to discover new things that have to be explained. We have been more successful in dis-covering new things than in explaining old ones.

The computer incidentially caused a revolution in physics itself, increasing the power of physical theories to interpret experiments and predict phenomena. Thecomputer and the algorithms are prime example of an intellectual tool.

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Vision: Simulation Triangle@FZJ

Research AreaSimulation

JSF GRS

IAS

NICGAUSS

PACE

DEISA

JARA-SIMJPSS

Th. Lippert & S.Blügel

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Institute for Advanced Simulation (IAS)

• Computational Biotechnology • Computational Biophysics• Computational Nanoscience• Quantum Computing• Computational Neuroscience• Computation Engineering

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22 Artikel in Science

0

1

2

3

4

5

19851986198719881989199019911992199319941995199619971998199920002001200220032004200520062007

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54 Artikel in Nature

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1

2

3

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1974197519761977197819791980198119821983198419851986198719881989199019911992199319941995199619971998199920002001200220032004200520062007

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• Markus Heide• Gustav Bihlmayer

Collaboration: Paolo Ferriani Stefan Heinze Matthias Bode Kirsten von Bergmann Nacho Pascual Ph. Hofmann

Helmholtz Association of Research Centers (HGF)Deutsche Forschungsgemeinschaft (DFG)

Sponsers:

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www.fz-juelich.de/iff/e_th1Theory-1 Group at IFF