J. Dolinšek 1

Anisotropic Physical Properties of Decagonal Quasicrystals

Janez Dolinšek Jožef Stefan Institute, University of Ljubljana, Slovenia

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Slovenia

area: 20.000 km2

population: 2 million

Ljubljana

Julian Alps Lake Bled Adriatic sea Lipizaner horses

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“Jožef Stefan” Institute, Ljubljana, Slovenia

staff: 850

revenues (2012): 52 MEur

physics chemistry biology

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Structure of decagonal quasicrystals

Geometrical description:

periodic stacking of quasiperiodic atomic layers

periodic 10-fold directionquasiperiodic atomic layers

P

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Investigated phase

Decagonal quasicrystal d-Al-Co-Ni:

- symmetry: decagonal

- chemical composition (at. %): Al70Co10Ni20

2 atomic layers within one periodic unit of 0.4 nm along 105 axis

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Physical properties investigated:

- electrical resistivity ρ(T)

- magnetism χ(T), M(H)

- thermoelectric power S(T)

- Hall coefficient RH(T)

- thermal conductivity κ(T)

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Anisotropic physical properties of d-Al-Co-Ni

measurements performed along four crystallographic directions

(three “in-plane” and the stacking “10-fold” direction)

... stacking direction P

P

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d-Al-Co-Ni: samples preparation

P. Gille, G. Meisterernst, N. Faber, J. Crystal Growth 275, 224 (2005)

P

P

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Symmetry analysis

P

General form of a tensorial physical property (2nd rank tensor) for a decagonal point group:

b

a

a

Tij00

00

00

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d-Al70Co10Ni20: symmetry analysis by 27Al NMR

27Al NMR spectrum

central linecentral line

satellites

M. Bobnar et al., Phys. Rev. B 85, 024205 (2012)

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d-Al70Co10Ni20: orientation-dependent 27Al NMR spectra

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d-Al70Co10Ni20: orientation-dependent 27Al NMR satellite intensity

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d-Al70Co10Ni20: orientation-dependent 27Al NMR satellite intensity

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d-Al70Co10Ni20: electrical resistivity

P

P

T-dependent resistivity in the Q plane

Theory: Model of slow charge carriers G. Trambly de Laissardière et al., Phys. Rev. Lett. 97, 026601 (2006)

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d-Al70Co10Ni20 :Hall coefficient

P

M. Bobnar et al., Phys. Rev. B 85, 024205 (2012)

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: d-Al70Co10Ni20 : thermal conductivity

P

M. Bobnar et al., Phys. Rev. B 85, 024205 (2012)

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Magnetization vs. magnetic field and magnetic susceptibility

P

P

Stronger diamagnetism for the field along 10-fold axis: atomic rings in the Q plane form diamagnetic circular current loops

W. Steurer et al., Acta Cryst. B 49, 661 (1993)

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Conclusions

- electrical, thermal and magnetic properties of d-Al-Co-Ni decagonal quasicrystal are highly anisotropic;

- stacking direction is the most conducting direction for the electricity and heat;

- origin of anisotropy is the anisotropic stacked-layer atomic structure.

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Coworkers and cooperation

J. Stefan Institute, Ljubljana

Stane Vrtnik

Matej Bobnar

Zvonko Jagličić

Ludwig-Maximilian University, Munich

Peter Gille

Institute of Physics, Zagreb

Ana Smontara