Two-electronic component behavior in the multiband FeSe0.42_{0.42}Te0.58_{0.58} superconductor

We report X-band EPR and $^{125}$Te and $^{77}$Se NMR measurements on single-crystalline superconducting FeSe$_{0.42}$Te$_{0.58}$ ($T_c$ = 11.5(1) K). The data provide evidence for the coexistence of intrinsic localized and itinerant electronic states. In the normal state, localized moments couple to itinerant electrons in the Fe(Se,Te) layers and affect the local spin susceptibility and spin fluctuations. Below $T_c$, spin fluctuations become rapidly suppressed and an unconventional superconducting state emerges in which $1/T_1$ is reduced at a much faster rate than expected for conventional $s$- or $s_\pm$-wave symmetry. We suggest that the localized states arise from the strong electronic correlations within one of the Fe-derived bands. The multiband electronic structure together with the electronic correlations thus determine the normal and superconducting states of the FeSe$_{1-x}$Te$_x$ family, which appears much closer to other high-$T_c$ superconductors than previously anticipated.Comment: 5 pages, 4 figure

Jahn-Teller orbital glass state in the expanded fcc Cs3C60 fulleride

The most expanded fcc-structured alkali fulleride, Cs3C60, is a Mott insulator at ambient pressure because of the weak overlap between the frontier t1u molecular orbitals of the C603− anions. It has a severely disordered antiferromagnetic ground state that becomes a superconductor with a high critical temperature, Tc of 35 K upon compression. The effect of the localised t1u3 electronic configuration on the properties of the material is not well-understood. Here we study the relationship between the intrinsic crystallographic C603− orientational disorder and the molecular Jahn–Teller (JT) effect dynamics in the Mott insulating state. The high-resolution 13C magic-angle-spinning (MAS) NMR spectrum at room temperature comprises three peaks in the intensity ratio 1:2:2 consistent with the presence of three crystallographically-inequivalent carbon sites in the fcc unit cell and revealing that the JT-effect dynamics are fast on the NMR time-scale of 10−5 s despite the presence of the frozen-in C603− merohedral disorder disclosed by the 133Cs MAS NMR fine splitting of the tetrahedral and octahedral 133Cs resonances. Cooling to sub-liquid-nitrogen temperatures leads to severe broadening of both the 13C and 133Cs MAS NMR multiplets, which provides the signature of an increased number of inequivalent 13C and 133Cs sites. This is attributed to the freezing out of the C603− JT dynamics and the development of a t1u electronic orbital glass state guided by the merohedral disorder of the fcc structure. The observation of the dynamic and static JT effect in the Mott insulating state of the metrically cubic but merohedrally disordered Cs3C60 fulleride in different temperature ranges reveals the intimate relation between charge localization, magnetic ground state, lifting of electronic degeneracy, and orientational disorder in these strongly-correlated systems

Improvement of contact resistance in flexible a-IGZO thin-film transistors by CF4/O2 plasma treatment

In this work, we analyze the effect of CF4/O2 plasma treatment on the contact interface between the amorphous Indium-Gallium-Zinc-Oxide (a-IGZO) semiconductor and Titanium-Gold electrodes. First, the influence of CF4/O2 plasma treatment is evaluated using transmission line structures and compared to pure O2 and CF4 plasma, resulting in a reduction of the contact resistance RC by a factor of 24.2 compared to untreated interfaces. Subsequently, the CF4/O2 plasma treatment is integrated in the a-IGZO thin-film transistor (TFT) fabrication process flow. We achieve a reduction of the gate bias dependent RC by a factor up to 13.4, which results in an increased current drive capability. Combined with an associated channel length reduction, the effective linear field-effect mobility is increased by up to 74.6% for the CF4/O2 plasma treated TFTs compared to untreated reference devices

Hadron and Quark Form Factors in the Relativistic Harmonic Oscillator Model

Nucleon, pion and quark form factors are studied within the relativistic harmonic oscillator model including the quark spin. It is shown that the nucleon charge, magnetic and axial form factors and the pion charge form factor can be explained with one oscillator parameter if one accounts for the scaling rule and the size of the constituent quarks.Comment: 9 pages, Latex, 3 postscript figures, DFTT 8/9

Diffracted diffraction radiation and its application to beam diagnostics

We present theoretical considerations for diffracted diffraction radiation and also propose an application of this process to diagnosing ultra-relativistic electron (positron) beams for the first tim

Experimental Study of Proton Irradiation on C3H/He Mice

開始ページ、終了ページ: 冊子体のページ付

Planar channelling of relativistic electrons in half-wave silicon crystal and corresponding radiation

New experimental data on planar channeling of 255 MeV electrons in a 0.74 µm Si Half-Wave Crystal (HWC) obtained at SAGA-LS facility are presented. The computer simulation showed that the angular distribution of electrons after penetration through the HWC revealed the number of unknown before peculiarities is connected with specific electron trajectories in HWC. These specific trajectories lead to specific radiation, the properties of which are analyzed

Calculation of the Aharonov-Bohm wave function

A calculation of the Aharonov-Bohm wave function is presented. The result is a series of confluent hypergeometric functions which is finite at the forward direction.Comment: 12 pages in LaTeX, and 3 PostScript figure

Channeling of Relativistic Electrons in Half-Wave Silicon Crystal and Corresponding Radiation

The new experiments on channeling of 255 MeV in a 0.7 ?m silicon half-wavelength crystal were performed at SAGA LS facility. Both experimental and simulated electron angular distribution after the crystal and corresponding radiation spectra reveal the number of peculiarities