Anisotropic Physical Properties of Decagonal Quasicrystals Janez Dolinšek
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Transcript of Anisotropic Physical Properties of Decagonal Quasicrystals Janez Dolinšek
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
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d-Al-Co-Ni: samples preparation
P. Gille, G. Meisterernst, N. Faber, J. Crystal Growth 275, 224 (2005)
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Symmetry analysis
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General form of a tensorial physical property (2nd rank tensor) for a decagonal point group:
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Tij00
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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
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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
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M. Bobnar et al., Phys. Rev. B 85, 024205 (2012)
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: d-Al70Co10Ni20 : thermal conductivity
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M. Bobnar et al., Phys. Rev. B 85, 024205 (2012)
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Magnetization vs. magnetic field and magnetic susceptibility
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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