7,140 research outputs found
Stable Existence of Phase IV inside Phase II under Pressure in CeLaB
We investigate the pressure effect of the electrical resistivity and
magnetization of CeLaB. The situation in which phase IV
stably exists inside phase II at H=0 T could be realized by applying a pressure
above GPa. This originates from the fact that the stability of
phase II under pressure is larger than those of phases IV and III. The results
seem to be difficult to reproduce by taking the four interactions of
-type AFO, -type AFQ, -type AFO, and AF
exchange into account within a mean-field calculation framework.Comment: 4 pages, 5 figures, to appear in J. Phys. Soc. Jpn. 79 (2010) No.
Preliminary experimental results of gas recycling subsystems except carbon dioxide concentration
Oxygen concentration and separation is an essential factor for air recycling in a controlled ecological life support system (CELSS). Furthermore, if the value of the plant assimilatory quotient is not coincident with that of the animal respiratory quotient, the recovery of oxygen from the concentrated CO2 through chemical methods will become necessary to balance the gas contents in a CELSS. Therefore, oxygen concentration and separation equipment using Salcomine and O2 recovery equipment, such as Sabatier and Bosch reactors, were experimentally developed and tested
A Cosmic Microwave Background Radiation Polarimeter Using Superconducting Bearings
Measurements of the polarization of the cosmic microwave background (CMB)
radiation are expected to significantly increase our understanding of the early
universe. We present a design for a CMB polarimeter in which a cryogenically
cooled half wave plate rotates by means of a high-temperature superconducting
(HTS) bearing. The design is optimized for implementation in MAXIPOL, a
balloon-borne CMB polarimeter. A prototype bearing, consisting of commercially
available ring-shaped permanent magnet and an array of YBCO bulk HTS material,
has been constructed. We measured the coefficient of friction as a function of
several parameters including temperature between 15 and 80 K, rotation
frequency between 0.3 and 3.5 Hz, levitation distance between 6 and 10 mm, and
ambient pressure between 10^{-7} and 1 torr. The low rotational drag of the HTS
bearing allows rotations for long periods of time with minimal input power and
negligible wear and tear thus making this technology suitable for a future
satellite mission.Comment: 6 pages, IEEE-Transactions of Applied Superconductivity, 2003, Vol.
13, in pres
Novel phase transition and the pressure effect in YbFe2Al10-type CeT2Al10 (T=Fe, Ru, Os)
We have succeeded in growing single crystals of orthorhombic CeT2Al10 (T=Fe,
Ru, Os) by Al self-flux method for the first time, and measured the electrical
resistivity at pressures up to 8 GPa, the magnetic susceptibility and specific
heat at ambient pressure. These results indicate that CeT2Al10 belongs to the
heavy fermion compounds. CeRu2Al10 and CeOs2Al10 show a similar phase
transition at T0 = 27.3 and 28.7 K, respectively. The temperature dependences
in the ordered phases are well described by the thermally activated form,
suggesting that partial gap opens over the Fermi surfaces below T0. When
pressure is applied to CeRu2Al10, T0 disappears suddenly between 3 and 4 GPa,
and CeRu2Al10 turns into a Kondo insulator, followed by a metal. The similarity
of CeT2Al10 under respective pressures suggests a scaling relation by some
parameter controlling the unusual physics in these compounds.Comment: 9 pages, 5 figure
Kondo effect in CeX (X=S, Se, Te) studied by electrical resistivity under high pressure
We have measured the electrical resistivity of cerium monochalcogenices, CeS,
CeSe, and CeTe, under high pressures up to 8 GPa. Pressure dependences of the
antiferromagnetic ordering temperature , crystal field splitting, and
the anomaly of the Kondo effect have been studied to cover the whole
region from the magnetic ordering regime at low pressure to the Fermi liquid
regime at high pressure. initially increases with increasing pressure,
and starts to decrease at high pressure as expected from the Doniach's diagram.
Simultaneously, the behavior in the resistivity is enhanced, indicating
the enhancement of the Kondo effect by pressure. It is also characteristic in
CeX that the crystal field splitting rapidly decreases at a common rate
of K/GPa. This leads to the increase in the degeneracy of the state
and further enhancement of the Kondo effect. It is shown that the pressure
dependent degeneracy of the state is a key factor to understand the
pressure dependence of , Kondo effect, magnetoresistance, and the peak
structure in the temperature dependence of resistivity.Comment: 9 pages, 5 figures, accepted for publication in J. Phys. Soc. Jp
Atomic displacements and lattice distortion in the magnetic-field-induced charge ordered state of SmRuP
Structural properties of SmRuP in the anomalous magnetic ordered
phase between K and K in magnetic fields has
been studied by x-ray diffraction. Atomic displacements of Ru and P, reflecting
the field-induced charge order of the electrons, have been deduced by
analyzing the intensities of the forbidden Bragg peaks, assuming a cubic space
group . Also, by utilizing high-resolution x-ray diffraction
experiment, we observed a splitting of fundamental Bragg peaks, clarifying that
the unit cell in the magnetic ordered phase is rhombohedral elongated along the
axis. Responses of the rhombohedral domains to the magnetic
field, which reflects the direction of the magnetic moment, is studied in
detail.Comment: 11 pages, 11 figures, accepted for publication in PR
- …