13 research outputs found
Interpretation of some Yb-based valence-fluctuating crystals as approximants to a dodecagonal quasicrystal
The hexagonal ZrNiAl-type (space group: P-62m) and the tetragonal
Mo2FeB2-type (space group: P4/mbm) structures, which are frequently formed in
the same Yb-based alloys and exhibit physical properties related to
valence-fluctuation, can be regarded as approximants of a hypothetical
dodecagonal quasicrystal. Using Pd-Sn-Yb system as an example, a model of
quasicrystal structure has been constructed, of which 5-dimensional crystal
(space group: P12/mmm, aDD=5.66 {\AA} and c=3.72 {\AA}) consists of four types
of acceptance regions located at the following crystallographic sites; Yb
[00000], Pd[1/3 0 1/3 0 1/2], Pd[1/3 1/3 1/3 1/3 0] and Sn[1/2 00 1/2 1/2]. In
the 3-dimensional space, the quasicrystal is composed of three types of
columns, of which c-projections correspond to a square, an equilateral triangle
and a 3-fold hexagon. They are fragments of two known crystals, the hexagonal
{\alpha}-YbPdSn and the tetragonal Yb2Pd2Sn structures. The model of the
hypothetical quasicrystal may be applicable as a platform to treat in a unified
manner the heavy fermion properties in the two types of Yb-based crystals.Comment: 19 pages, 6 figure
Ordered ground state configurations of the asymmetric Wigner bilayer system -- revisited: an unsupervised clustering algorithm analysis
We have re-analysed the rich plethora of ground state configurations of the
asymmetric Wigner bilayer system that we had recently published in a related
diagram of states [M. Antlanger \textit{et al.}, Phys. Rev. Lett. \textbf{117},
118002 (2016)], comprising roughly 60~000 state points in the phase space
spanned by the distance between the plates and the charge asymmetry parameter
of the system. In contrast to this preceding contribution where the
classification of the emerging structures was carried out ``by hand'', we have
used this time machine learning concepts, notably based on a principal
component analysis and a -means clustering approach: using a 30-dimensional
feature vector for each emerging structure (containing relevant information,
such as the composition of the configuration as well as the most relevant order
parameters) we were able to re-analyse these ground state configurations in a
considerably more systematic and comprehensive manner than we could possibly do
in the previously published classification scheme. Indeed we were now able to
identify new structures in previously unclassified regions of the parameter
space and could considerably refine the previous classification scheme,
identifying thereby a rich wealth of new emerging ground state configurations.
Thorough consistency checks confirm the validity of the newly defined diagram
of states
Icosahedral quasicrystals: tilings of icosahedral clusters
Tiling of four canonical cells, proposed by Henley [1], is a promising alternative to the Penrose-tiling and six-dimensional approaches to the structure of icosahedral quasicrystals. In this paper we briefly summarize the firts results of the structural modeling in the i-AlMnSi and i-AlCuLi systems. The understanding of the structure of the stable quasicrystals, like i-AlCuFe and i-AlPdMn, is of course of greatest interest; a possible canonical-cell approach is outlined
Interpretation of some Yb-based valence-fluctuating crystals as approximants to a dodecagonal quasicrystal
International audienc
Phason space analysis and structure modelling of 100 Å-scale dodecagonal quasicrystal in Mn-based alloy
1/1 approximant.
Lattice dynamics of the Zn-Mg-Sc icosahedral quasicrystal and its Zn-Sc periodi