1,898 research outputs found
Paramagnetic Phase of a Heavy-Fermion Compound, CeFePO, Probed by 57Fe M\"{o}ssbauer Spectroscopy
57Fe M\"{o}ssbauer spectroscopy was applied to an iron-based layered compound
CeFePO. At temperatures from 9.4 to 293 K, no magnetic splitting was observed
in the M\"ossbauer spectra of CeFePO indicating a paramagnetic phase of the Fe
magnetic sublattice. All the spectra were fitted with a small quadrupole
splitting, and the Debye temperature of CeFePO was found to be \sim448 K. The
isomer shift at room temperature, 0.32 mm/s, was almost equal to those of
LnFeAsO (Ln = La, Ce, Sm). Comparing s-electron density using the isomer shifts
and unit cell volumes, it was found that the Fe of CeFePO has a similar valence
state to other layered iron-based quaternary oxypnictides except LaFePO
Nickel-based phosphide superconductor with infinite-layer structure, BaNi2P2
Analogous to cuprate high-Tc superconductors, a NiP-based compound system has
several crystals in which the Ni-P layers have different stacking structures.
Herein, the properties of BaNi2P2 are reported. BaNi2P2 has an infinite-layer
structure, and shows a superconducting transition at ~3 K. Moreover, it
exhibits metallic conduction and Pauli paramagnetism in the temperature range
of 4-300 K. Below 3 K, the resistivity sharply drops to zero, and the magnetic
susceptibility becomes negative, while the volume fraction of the
superconducting phase estimated from the diamagnetic susceptibility reaches
~100 vol.% at 1.9 K. These observations substantiate that BaNi2P2 is a bulk
superconductor.Comment: 9 pages, 4 figures, Solid State Communications, in press. Received 4
March 2008. Accepted 2 May 2008. Available online 14 May 200
Large Seebeck coefficients in Iron-oxypnictides : a new route towards n-type thermoelectric materials
The iron-oxypnictide compounds, recently reported as a new class of
superconductors when appropriately doped, exhibit large Seebeck coefficients,
of the order of -100 microV/K, while keeping good electrical conductivity.
Their power factor shows a peak at low temperatures, suggesting possible
applications of these materials in thermoelectric cooling modules in the liquid
nitrogen temperature range
^{75}As NMR study of the growth of paramagnetic-metal domains due to electron doping near the superconducting phase in LaFeAsO_{1-x}F_{x}
We studied the electric and magnetic behavior near the phase boundary between
antiferromagnetic (AF) and superconducting (SC) phases for a prototype of
high-T_c pnictides LaFeAsO_{1-x}F_{x} by using nuclear magnetic resonance, and
found that paramagnetic-metal (PM) domains segregate from AF domains. PM
domains grow in size with increasing electron doping level and are accompanied
by the onset of superconductivity, and thus application of pressure or
increasing the doping level causes superconductivity. The existence of PM
domains cannot be explained by the existing paradigm that focuses only on the
relationship between superconductivity and antiferromagnetism. Based on orbital
fluctuation theory, the existence of PM domains is evidence of the
ferroquadrupole state.Comment: 5 figure
Nodal Gap in Fe-Based Layered Superconductor LaO_0.9F_{0.1-delta}FeAs Probed by Specific Heat Measurements
We report the specific heat measurements on the newly discovered Fe-based
layered superconductor LaO_0.9F_{0.1-delta}FeAs with the onset transition
temperature T_c \approx 28 K. A nonlinear magnetic field dependence of the
electronic specific heat coefficient gamma(H) has been found in the low
temperature limit, which is consistent with the prediction for a nodal
superconductor. The maximum gap value Delta_0 \approx 3.40.5 meV was
derived by analyzing gamma(H) based on the d-wave model. We also detected the
electronic specific heat difference between 9 T and 0 T in wide temperature
region, a specific heat anomaly can be clearly observed near T_c. The Debye
temperature of our sample was determined to be about 315.7 K. Our results
suggest an unconventional mechanism for this new superconductor.Comment: 4 pages, 4 figures,Corrected typo
A Review of Spinal ROM Measurement Tools
Physical therapists rely on measurements to communicate with one another, establish patient status, predict treatment response, document treatment efficacy, and claim scientific credibility for the profession. Therefore, the quality of measurements should be of great concern to physical therapists and, hence, therapists should be able to examine the quality of measurement tools they are using critically. A variety of measurement tools are being utilized in physical therapy to quantify spinal mobility; however, there is no clarity as to which of the tools are optimal. In particular, the spinal range of motion measurement tools will be examined because of the high occurrence and high cost of low back injuries.
The spinal range of motion measurement tools reviewed in this study include goniometers, flexible rulers, inclinometers, motion analysis systems, the Isotechnologies B-200, and the Spinoscope. The use of each of these measurement tools has advantages and disadvantages in a clinical setting. The reliability and validity of a measurement tool should be the most important considerations, but individual clinical needs and available resources also need to be considered when choosing an appropriate spinal range of motion measurement tool. If all these factors are considered, the author recommends the use of inclinometers since many studies show the inclinometer to be both reliable and valid. The EDI 320, in particular, is recommended for its ease of application. Finally, even if a tool is shown to be reliable and valid, established protocols for measurement techniques should be followed by each clinical staff member
Superconductivity at 36 K in Gadolinium-arsenide Oxides GdOFFeAs
In this paper we report the fabrication and superconducting properties of
GdOFFeAs. It is found that when x is equal to 0.17,
GdOFFeAs is a superconductor with the onset transition
temperature T 36.6K. Resistivity anomaly near 130K was
observed for all samples up to x = 0.17, such a phenomenon is similar to that
of LaOFFeAs. Hall coefficient indicates that
GdOFFeAs is conducted by electron-like charge carriers.Comment: 3 pages, 4 figure
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