333 research outputs found
Testing of a novel web browser interface for the Chinese market
This paper compares the perspicacity, appropriateness and preference of web browser icons from leading software providers with those of a culture-specific design. This online study was conducted in Taiwan and involved 103 participants, who were given three sets of web browser icons to review, namely Microsoft Internet Explorer, Macintosh Safari, and culturally specific icons created using the Culture-Centred Design methodology. The findings of the study show that all three sets have generally high recognition rates, but that some icon functions (e.g. Go/Visit and Favourite) in all three sets have poor recognition rates and are considered inappropriate
Magnetic Phase Diagrams of Multiferroic Hexagonal RMnO3 (R=Er, Yb, Tm, and Ho)
The magnetic phase diagrams of RMnO3 (R = Er, Yb, Tm, Ho) are investigated up
to 14 Tesla via magnetic and dielectric measurements. The stability range of
the AFM order below the Neel temperature of the studied RMnO3 extends to far
higher magnetic fields than previously assumed. Magnetic irreversibility
indicating the presence of a spontaneous magnetic moment is found near 50 K for
R=Er, Yb, and Tm. At very low temperatures and low magnetic fields the phase
boundary defined by the ordering of the rare earth moments is resolved. The
sizable dielectric anomalies observed along all phase boundaries are evidence
for strong spin-lattice coupling in the hexagonal RMnO3. In HoMnO3 the strong
magnetoelastic distortions are investigated in more detail via magnetostriction
experiments up to 14 Tesla. The results are discussed based on existing data on
magnetic symmetries and the interactions between the Mn-spins, the rare earth
moments, and the lattice.Comment: 23 pages, 16 figures, to be published in JMR's Aug. focus issue on
multiferroic
Magnetic phase diagrams of the Kagome staircase compound Co3V2O8
At zero magnetic field, a series of five phase transitions occur in Co3V2O8.
The Neel temperature, TN=11.4 K, is followed by four additional phase changes
at T1=8.9 K, T2=7.0 K, T3=6.9 K, and T4=6.2 K. The different phases are
distinguished by the commensurability of the b-component of its spin density
wave vector. We investigate the stability of these various phases under
magnetic fields through dielectric constant and magnetic susceptibility
anomalies. The field-temperature phase diagram of Co3V2O8 is completely
resolved. The complexity of the phase diagram results from the competition of
different magnetic states with almost equal ground state energies due to
competing exchange interactions and frustration.Comment: Proceedings of the 2007 Conference on Strongly Correlated Electron
Systems, 2 pages, 2 figure
Pressure Effect on the Superconducting and Magnetic Transitions of the Superconducting Ferromagnet RuSr2GdCu2O8
The superconducting ferromagnet RuSr2GdCu2O8 was investigated at high
pressure. The intra-grain superconducting transition temperature, Tc, is
resolved in ac-susceptibility as well as resistivity measurements. It is shown
that the pressure shift of Tc is much smaller than that of other high-Tc
compounds in a similar doping state. In contrast, the ferromagnetic transition
temperature, Tm, increases with pressure at a relative rate that is about twice
as large as that of Tc. The high-pressure data indicate a possible competition
of the ferromagnetic and superconducting states in RuSr2GdCu2O8
Thermal expansion and pressure effect in MnWO4
MnWO4 has attracted attention because of its ferroelectric property induced
by frustrated helical spin order. Strong spin-lattice interaction is necessary
to explain ferroelectricity associated with this type of magnetic order.We have
conducted thermal expansion measurements along the a, b, c axes revealing the
existence of strong anisotropic lattice anomalies at T1=7.8 K, the temperature
of the magnetic lock-in transition into a commensurate low-temperature
(reentrant paraelectric) phase. The effect of hydrostatic pressure up to 1.8
GPa on the FE phase is investigated by measuring the dielectric constant and
the FE polarization. The low- temperature commensurate and paraelectric phase
is stabilized and the stability range of the ferroelectric phase is diminished
under pressure.Comment: 2 pages, 3 figures. SCES conference proceedings, houston, TX, 2007.
to be published in Physica
A Possible Crypto-Superconducting Structure in a Superconducting Ferromagnet
We have measured the dc and ac electrical and magnetic properties in various
magnetic fields of the recently reported superconducting ferromagnet
RuSr2GdCu2O8. Our reversible magnetization measurements demonstrate the absence
of a bulk Meissner state in the compound below the superconducting transition
temperature. Several scenarios that might account for the absence of a bulk
Meissner state, including the possible presence of a sponge-like non-uniform
superconducting or a crypto-superconducting structure in the chemically uniform
Ru-1212, have been proposed and discussed.Comment: 8 pages, 5 PNG figures, submitted to Proceedings of the 9th Japan-US
Workshop on High-Tc Superconductors, Yamanashi, Japan, October 13-15, 1999;
accepted for publication in Physica C (December 24, 1999
Superconductivity in the C32 Intermetallic Compounds AAl(2-x)Si(x), with A=Ca and Sr, and 0.6<x<1.2
The intermetallic compounds AAl2-xSix, where A = Ca, Sr or Ba, crystallize in
the C32 structure, same as the recently discovered MgB2 with a high
superconducting transition temperature of 39 K. For x = 1, superconductivity
has been observed in AAlSi with A = Ca and Sr, but not with A = Ba. The
transition temperatures are 7.8 and 5.1 K, respectively for CaAlSi and SrAlSi.
The CaAl2-xSix compound system display a Tc-peak at x = 1, a possible x-induced
electronic transition at x ~ 0.75 and a possible miscibility gap near x ~ 1.1
which results in a very broad superconducting transition. The Seebeck
coefficients of AAlSi indicate that their carriers are predominantly electrons
in nature, in contrast to the holes in MgB2.Comment: 10 pages, 6 figure
The Synthesis and Characterization of LiFeAs and NaFeAs
The newest homologous series of superconducting As-pnictides, LiFeAs (Li111)
and NaFeAs (Na111) have been synthesized and investigated. Both crystallize
with the layered tetragonal anti-PbFCl-type structure in P4/nmm space group.
Polycrystalline samples and single-crystals of Li111 and Na111 display
superconducting transitions at ~ 18 K and 12-25 K, respectively. No magnetic
order has been found in either compound, although a weak magnetic background is
clearly in evidence. The origin of the carriers and the stoichiometric
compositions of Li111 and Na111 were explored.Comment: submitted for publication in Physica C special issue on Fe-pnictide
Raman Phonons and Ageing-Related Surface Disorder in NaxCoO2
The polarized Raman spectra from ab and ac surfaces of single crystal NaxCoO2
(x~0.7), parent compound of recently discovered superconductor NaxCoO2.yH2O,
are reported and discussed. The crystals were hexagon platelets of typical size
3x3x0.1 mm. Three of the five (A1g+E1g+3E2g) Raman active phonons were
unambiguously identified at 458 (E1g), 494(E2g) and 574 (A1g) cm-1. The spectra
from ab and ac surfaces differ significantly and provide evidence that within
hours after preparation the ac surface, unlike the ab one, is strongly
disordered. Within several days the disorder extends over the ab surface too.Comment: 4 pages, 1 table, 4 figures. Physica C (accepted 26 September 2003
The Superconductivity, Intragrain Penetration Depth and Meissner Effect of RuSr2(Gd,Ce)2Cu2O10+delta
The hole concentration (p)(delta), the transition temperature Tc, the
intragrain penetration depth lambda, and the Meissner effect were measured for
annealed RuSr2(Gd,Ce)2Cu2O10+delta samples. The intragrain superconducting
transition temperature Tc} varied from 17 to 40 K while the p changed by only
0.03 holes/CuO2. The intragrain superfluid-density 1/lambda^2 and the
diamagnetic drop of the field-cooled magnetization across Tc (the Meissner
effect), however, increased more than 10 times. All of these findings are in
disagreement with both the Tc vs. p and the Tc vs. 1/lambda^2 correlations
proposed for homogeneous cuprates, but are in line with a possible
phase-separation and the granularity associated with it.Comment: 7 pages, 6 figures, accepted for publication in Phys. Rev. B (May 2,
2002
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