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@ARTICLE{Vrtnik:141269,
author = {Vrtnik, S. and Jazbec, S. and Jagodic, M. and Korelec, A.
and Hosnar, H. and Jaglicic, Z. and Jeglic, P. and
Feuerbacher, Michael and Mizutani, U. and Dolinsek, J.},
title = {{S}tabilization mechanism of γ-{M}g 17 {A}l 12 and β-{M}g
2 {A}l 3 complex metallic alloys},
journal = {Journal of physics / Condensed matter},
volume = {25},
number = {42},
issn = {1361-648X},
address = {Bristol},
publisher = {IOP Publ.},
reportid = {FZJ-2013-06463},
pages = {425703 -},
year = {2013},
abstract = {Large-unit-cell complex metallic alloys (CMAs) frequently
achieve stability by lowering the kinetic energy of the
electron system through formation of a pseudogap in the
electronic density of states (DOS) across the Fermi energy
εF. By employing experimental techniques that are sensitive
to the electronic DOS in the vicinity of εF, we have
studied the stabilization mechanism of two binary CMA phases
from the Al–Mg system: the γ-Mg17Al12 phase with 58 atoms
in the unit cell and the β-Mg2Al3 phase with 1178 atoms in
the unit cell. Since the investigated alloys are free from
transition metal elements, orbital hybridization effects
must be small and we were able to test whether the alloys
obey the Hume-Rothery stabilization mechanism, where a
pseudogap in the DOS is produced by the Fermi
surface–Brillouin zone interactions. The results have
shown that the DOS of the γ-Mg17Al12 phase exhibits a
pronounced pseudogap centered almost exactly at εF, which
is compatible with the theoretical prediction that this
phase is stabilized by the Hume-Rothery mechanism. The
disordered cubic β-Mg2Al3 phase is most likely entropically
stabilized at high temperatures, whereas at lower
temperatures stability is achieved by undergoing a
structural phase transition to more ordered rhombohedral β'
phase at 214 ° C, where all atomic sites become fully
occupied. No pseudogap in the vicinity of εF was detected
for the β' phase on the energy scale of a few 100 meV as
determined by the 'thermal observation window' of the
Fermi–Dirac function, so that the Hume-Rothery
stabilization mechanism is not confirmed for this compound.
However, the existence of a much broader shallow pseudogap
due to several critical reciprocal lattice vectors
$\buildrel{\rightharpoonup}\over{G} $ that simultaneously
satisfy the Hume-Rothery interference condition remains the
most plausible stabilization mechanism of this phase. At Tc
= 0.85 K, the β' phase undergoes a superconducting
transition, which slightly increases the cohesive energy and
may contribute to relative stability of this phase against
competing neighboring phases.},
cin = {PGI-5},
ddc = {530},
cid = {I:(DE-Juel1)PGI-5-20110106},
pnm = {424 - Exploratory materials and phenomena (POF2-424)},
pid = {G:(DE-HGF)POF2-424},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000325337700016},
doi = {10.1088/0953-8984/25/42/425703},
url = {https://juser.fz-juelich.de/record/141269},
}