Pseudo-gaps in crystalline and quasicrystalline alloys

Belin, E.; Dankházi, Zoltán; Sadoc, A.

doi:10.1016/0921-5093(94)90723-4

Cited by 14 publications

(3 citation statements)

References 16 publications

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“…Does the self-similarity of the structure require a new approach, different from the band-structure approach in crystals or from localization in disordered solids? Band structure calculations performed for approximant phases (Fujiwara 1989, Fujiwara and Yokokawa 1991, Hafner and Krajci 1992, 1993 are in line with the existence of the pseudo-gap observed experimentally at the Fermi level (E F ) (Belin and Traverse 1991, Belin et al 1992, 1994a, b, Belin-Ferré et al 1996. Current interpretations invoke a Hume-Rothery mechanism (HR), optimum in the case of quasicrystals because of the high multiplicity of the Bragg planes resulting from icosahedral symmetry (Friedel and Dénoyer 1987).…”

Section: Introductionsupporting

confidence: 76%

“…Indeed, it has been shown (Friedel 1992, Trambly de Laissardière et al 1995 that the presence of TM d states of energies close to the gap, coupled to the sp states, results in an increase of the magnitude of the potential acting on the Fermi electrons and consequently an increase of the width of the resulting pseudo-gap. Previous experiments on Al-TM alloys have revealed indeed the strong Al p-TM d hybridization at E F , the result of which is to repel the electronic states on both sides of the Fermi level, giving rise to an enhanced pseudo-gap (Belin et al 1992, 1994a. The p-d hybridization is even responsible for the opening of an almost true gap in Al 2 Ru and Ga 2 Ru semiconductors (Nguyen Manh et al 1992, Fournée et al 1997.…”

Section: Resultsmentioning

confidence: 91%

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Study of Al-Cu Hume-Rothery alloys and their relationship to the electronic properties of quasicrystals

Fournée

Belin-Ferré

Dubois

1998

J. Phys.: Condens. Matter

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The stability of quasicrystals is related to the Hume-Rothery mechanism known to take place in many intermetallics, especially Al-Cu alloys. In order to assess to what extent the electronic density of states in aperiodic Al-Cu-Fe compounds is sensitive to Hume-Rothery stabilization, we present experimental measurements by soft x-ray emission and absorption spectroscopies of the aluminium electronic states in a series of Al-Cu crystalline compounds. Some of them, like icosahedral Al-Cu-Fe, are characterized by nearly spherical Brillouin zones. We observe the opening of a narrow but definite pseudo-gap in such Al-Cu compounds. We point out a strong interaction between Cu d states and the Al states in the middle of the valence band which is well described by a Fano-like effect. Some other characteristic features of our spectra are interpreted on the basis of band structure calculations. A comparison to previous data published for quasicrystalline and approximant phases stresses the importance for the stability of these compounds of sp-d hybridization at the Fermi level. It also leads to the conclusion that the effect of Hume-Rothery interaction is dramatically enhanced by the hierarchical structure of quasicrystals rather than by the almost spherical shape of the Brillouin zone.

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Section: Introductionsupporting

confidence: 76%

Section: Resultsmentioning

confidence: 91%

Study of Al-Cu Hume-Rothery alloys and their relationship to the electronic properties of quasicrystals

Fournée

Belin-Ferré

Dubois

1998

J. Phys.: Condens. Matter

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“…In contrast to these marked differences, as outlined above, photoemission or x-ray emission spectroscopy (in general of about 0.3-0.5 eV resolution) did not reveal significant differences among the three species in their electronic DOS near E F , which were characterized by wide pseudogaps of about 1 eV [16][17][18]22].…”

Section: Sample Preparation and Characterizationmentioning

confidence: 99%

Tunnelling and point contact spectroscopy of the density of states in quasicrystalline alloys

Escudero

Lasjaunias

Calvayrac

et al. 1999

J. Phys.: Condens. Matter

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Point contact and tunnelling experiments performed at low temperatures were used to study the electronic behaviour of the icosahedral quasicrystalline alloys AlPdRe, AlCuFe, and AlPdMn. With samples of high quality we observed at low temperatures a zero-bias anomaly that we related to the decrease of the electronic density of states (DOS) due to the electron-electron interaction. This interaction tends to diminish the DOS at the Fermi level and can be seen as the energy pseudogap of the alloy. Our experiments indicate that the DOS is strongly modified near and consists of a spiky feature in a broad pseudogap, with the width of the feature of the order of 100 meV or even larger for the AlPdRe, whereas it is as small as 20-22 meV for Al-Cu-Fe and 17-20 meV for Al-Pd-Mn. The broad pseudogap has widths larger than 400 meV for AlPdRe, whereas for AlCuFe it is about 80-90 meV and for AlPdMn it is of the order of 110-122 meV. The studies were performed on three samples of the compositions , , and . The junctions were of the types alloy-Au(In, Al) and alloy-insulator-Au(In, Al), and were studied at different temperatures between that of liquid nitrogen and 2 K, and even to 400 mK for the AlCuFe alloy.

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