266 research outputs found
Low-Temperature X-ray Crystal Structure Analysis of the Cage-Structured Compounds MBe13 (M = La, Sm, and U)
The beryllides MBe13 (M = rare earths and actinides) crystallize in a
NaZn13-type cubic structure, which can be categorized as a cage-structured
compound. In this study, powder X-ray diffraction measurements have been
performed on LaBe13, SmBe13, and UBe13 in the temperature range between 7 and
300 K in order to investigate their crystallographic characteristics
systematically. They keep the NaZn13-type cubic structure down to the lowest
temperature. We estimated their Debye temperature to be 600 - 750 K from
analyses of the temperature dependence of a lattice parameter, being in good
agreement with the values reported previously. Rietveld refinements on the
obtained powder patterns revealed that the M atom in the 8a site is located in
an almost ideal snub cube formed by 24 Be atoms in the 96i site, whose caged
structure is unchanged even at the low temperatures. In addition, it is argued
from the temperature variation of an isotropic mean-square displacement
parameter that the MBe13 compounds commonly have a low-energy phonon mode,
which can be described by a model assuming an Einstein oscillation of the M
atom with a characteristic temperature of ~ 160 K.Comment: 8 pages with 6 figures and 2 table
Novel slow dynamics of phase transition in the partially ordered frustrated magnet DyRu2Si2
DyRu2Si2 is a frustrated magnet to exhibit multiple magnetic phase transition
in zero and finite magnetic fields. We investigated and characterized the phase
transition between the partially-ordered antiferromagnetic phases at zero field
by ac susceptibility measurements. Detailed ac susceptibility measurements
reveal the novel critical dynamics of the phase transition; extremely slow
dynamics with the relaxation time in the order of 10-100 msec, speed-up of the
dynamics on cooling indicating its non-thermally activated origin and growing
of the ferromagnetic correlations towards the phase transition temperature. On
the basis of these findings, we propose the novel phase transition process,
namely, the spontaneous striped-arrangement of the precedently emergent
"belt-like" ferromagnetic spin texture.Comment: Accepted by JPSJ
URL:https://journals.jps.jp/doi/10.7566/JPSJ.92.09470
Single crystal synthesis and magnetic properties of Co²⁺-substituted and non-substituted magnetoplumbite-type Na–La ferrite
Single crystals of magnetoplumbite-type Na–La ferrite with and without Co doping were grown by the flux method. Wave length dispersive X-ray analysis reveals that Na and La are present in the ratio of Na/La = 0.25–0.41, and Co is successfully substituted for Fe. Magnetization measurements using single crystals indicate uniaxial magnetic anisotropy in these materials. A metamagnetic transition for the hard-axis magnetization was observed in non Co²⁺-substituted samples at around 7 kOe due to the magnetic free energy double minima originating from the Fe²⁺ ion. The successful introduction of Co²⁺ enhances the uniaxial magnetic anisotropy favorable for permanent magnets
Doping Dependence of the in-Plane Transition in CoSnS
In CoSnS two transitions are observed, the main one to a
ferromagnetic state at K and the second one, involving in-plane
components at K. We follow their doping dependence as Sn is
replaced with In, which causes a reduction of and . Importantly,
both transitions follow the same doping dependence, indicating a single energy
scale involved with both processes.Comment: accepted as a short note in JPSJ; a continuation of work published in
arXiv:2211.01483 and https://doi.org/10.1103/PhysRevB.106.L18040
TiAl金属間化合物の強度評価へのX線回折法の適用と弾性的性質の結晶学的考察
取得学位:博士(工学),学位授与番号:博甲第230号,学位授与年月日:平成10年3月25日,学位授与年:199
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