608 research outputs found
Spatially Inhomogeneous Superconducting State near in UPdAl
We have performed Al-NMR measurements on single-crystalline
UPdAl with the field parallel to the axis to investigate the
superconducting (SC) properties near the upper critical field of
superconductivity . The broadening of the NMR linewidth below 14~K
indicates the appearance of the internal field at the Al site, which originates
from the antiferromagnetically ordered moments of U 5 electrons. In the SC
state well below = 3.4~T, the broadening of the NMR linewidth
due to the SC diamagnetism and a decrease in the Knight shift are observed,
which are well-understood by the framework of spin-singlet superconductivity.
In contrast, the Knight shift does not change below , and the NMR
spectrum is broadened symmetrically in the SC state in the field range of 3~T
. The unusual NMR spectrum near
suggests that a spatially inhomogeneous SC state such as the
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state would be realized.Comment: 5 pages, 5 figure
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
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