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Www.fz-juelich.de/iff/e_th1 Bad Neuenahr June -2007 Sinn für Drehungen im Nanokosmos Stefan Blügel IFF-I, Institut für Festkörperforschung.

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Präsentation zum Thema: "Www.fz-juelich.de/iff/e_th1 Bad Neuenahr June -2007 Sinn für Drehungen im Nanokosmos Stefan Blügel IFF-I, Institut für Festkörperforschung."—  Präsentation transkript:

1 Bad Neuenahr June Sinn für Drehungen im Nanokosmos Stefan Blügel IFF-I, Institut für Festkörperforschung

2 Bad Neuenahr June Marilyn Monroe Encore Celebrity Images

3 Bad Neuenahr June Marilyn Monroe Andy Warhol

4 Bad Neuenahr June Reminder : Chirality An object that cannot be superimposed on its mirror image mirror Chiral objects Nonsuperimposable mirror images mirror Nonchiral objects superimposable mirror images

5 Bad Neuenahr June Chirale Moleküle

6 Bad Neuenahr June Chirale Moleküle

7 Bad Neuenahr June Reminder : Parity violation 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:

8 Bad Neuenahr June Drehimpuls L = m (v x r) t  -t  v  -v  L  -L Time-inversion symmetry (1) Rechtsdrehung vorwärts Rechtsdrehung rückwärts L r v t  -t  v  -v  L  -L t  -t

9 Bad Neuenahr June Time-inversion symmetry (2) Rechtsdrehung rückwärts Linksdrehung vorwärts Der zeitumgekehrte Prozess lässt sich physikalisch realisieren!

10 Bad Neuenahr June Spatial inversion (parity) Der spiegelbildliche Prozess (hier ebenfalls die umgekehrte Drehung) ist ebenfalls physikalisch realisierbar. Inversion hier veranschaulicht an hand der ähnlichen Spiegelung

11 Bad Neuenahr June Helizität des Lichts Die Intensität des Lichts bestimmt die Anzahl der Photonen, die wie Teilchen agieren Lichtgeschwindigkeit 50% aller Photonen haben Chiralität= -1 50% aller Photonen haben Chiralität= +1

12 Bad Neuenahr June Der Photoelektrische Effekt Metalloberfläche Die Intensität des Lichts bestimmt die Anzahl der Elektronen 50% aller Elektronen haben Chiralität=-1/2 50% aller Elektronen haben Chiralität= +1/2

13 Bad Neuenahr June Spiral Galaxies

14 Bad Neuenahr June Parity Violation at Surfaces time inversion T mirror reflection R time inversion T mirror reflection R time inversion T E =E(TR) E E ≠E(TR) mirror reflection R

15 Bad Neuenahr June Homochiral Magnetic State

16 Bad Neuenahr June 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 or is it smoke of theory? oDoes ferro- or antiferromagnetism exists at surfaces at all ? oFor domain walls, chirality can be broken i.e. there should be only walls of one type

17 Bad Neuenahr June Complete Picture Heisenberg Exchange Dzyaloshinskii Moriya-Exchange Magneto- Crystalline Anisotropy Dipol-Dipol Anisotropy

18 Bad Neuenahr June Phase Diagramme M. Heide, G. Bihlmayer and S. Blügel

19 Bad Neuenahr June Model system: Monolayer Mn on W(110) 0.75 ML meV/Atom ± 0 meV/Atom + 70 meV/Atom Magnetic Configuration : Pseudomorphic Growth: M. Bode et al., Surf. Sci. 432, 8 (1999). Cu-Atome Vakuum Mn-Atome

20 Bad Neuenahr June Imaging Mn/W(110) Non-magnetic W-Tip S. Heinze, M. Bode et al., Science 288, 1805 (2000).

21 Bad Neuenahr June Quantum Mechanics of Electrons: Many-body problem iron atom: 26 electron wave-function: Ψ(r 1,...r 26 ) store only 10 values per coordinate: values assume each value could be stored in a single H atom: memory heavier than the milky way

22 Bad Neuenahr June Density Functional Theory (DFT) Total Energy: Secular Equation: Density: Energy is functional of electron density n and external parameters such as lattice constants, atoms positions, magnetization direction… CPU time proportional to N 3 : Selfconsistency loop

23 Bad Neuenahr June The Nobel Prize in Chemistry 1998 "for his development of the density- functional theory" "for his development of computational methods in quantum chemistry" Walter KohnJohn A. Pople

24 Bad Neuenahr June Revolution in Computing Power: cutting supercomputing in nanomagnetism A. E. Brenner, Physics Today, October 1996 $1K

25 Bad Neuenahr June Imaging the Magnetic Ground State of 1ML-Mn/W(110) Non-magnetic W-Tip Magnetic Fe-Tip î First experimental Proof of the 2D-AFM! S.Heinze, M. Bode, A. Kubetzka, X. Nie, O. Pietsch, S.Blügel, Wiesendanger, Science 288 (2000)

26 Bad Neuenahr June Revolution in Computing Power: cutting supercomputing in nanomagnetism A. E. Brenner, Physics Today, October 1996 $1K

27 Bad Neuenahr June New Interaction discovered Bode, Heide, von Bergmann, Ferriani, Heinze, Bihlmayer, Kubetzka, Pietzsch, Bl ü gel, Wiesendanger, cycloidal spiral x Nature 447, 190 (2007) |L>|R> FM/AFM E(c) c JUMP

28 Bad Neuenahr June -2007

29 Bad Neuenahr June Tool-driven revolutions Dyson, F., Imagined Worlds, Harvard University Press, Cambridge, MA, 1997, pgs 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 explain old 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. The computer and the algorithms are prime example of an intellectual tool.

30 Bad Neuenahr June Vision: Simulation Research Area Simulation JSF GRS IAS NIC GAUSS PACE DEISA JARA-SIM JPSS Th. Lippert & S.Blügel

31 Bad Neuenahr June Institute for Advanced Simulation (IAS) Computational Biotechnology Computational Biophysics Computational Nanoscience Quantum Computing Computational Neuroscience Computation Engineering

32 Bad Neuenahr June -2007

33 Bad Neuenahr June -2007

34 Bad Neuenahr June 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:

35 Bad Neuenahr June Theory-1 Group at IFF


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