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Metastable filamentary superconductivity with Tc = 10.2 K was observed in SrPt2Ge2. This is the highest Tc reported outside the iron-based 122-layer compounds. The stable phase for this compound is a non-superconducting monoclinic LaPt2Ge2-type structure with lattice parameters a = 0.4401(4) nm, b = 0.4435(4) nm, c = 0.9764(10) nm, β = 90.5°-90°. Weak diamagnetic shielding signal indicates that superconductivity is not from the major monoclinic phase, but from the minor BaFe2As2-type body-center-tetragonal (122-bct) phase with a=0.44 nm, c=0.98 nm,β=90°. Investigation on the pseudoternary system Sr(Pd1-xPtx)2Ge2 suggests that the stable bct to monoclinic structure phase transition occurs near x = 0.15. For x<0.15 with bct phase, bulk Tc increases from 3.2 K for SrPd2Ge2 to 3.6 K for SrPd1.8Pt0.2Ge2. For x>0.15 with metastable filamentary bct phase, Tc increases from 7.5 K for x = 0.5 to 9.2 K for x = 0.7 and reaches a Tc maximum of 10.2 K for SrPt2Ge2. High Tc is due to a strong quasi-2D Pt-Ge-Pt 5dxz,yz-4p-5dxz,yz hybridization in the Pt-Ge layer with squeezed-along-c-axis PtGe4 tetrahedral crystal field and Pt-5d8 spin-orbital interaction in the metastable filamentary bct phase and is another example of multi-band (dxz/dyz/dxy) non-conventional s-wave superconductor. [ABSTRACT FROM AUTHOR]

Efficiency of tris (8-hydroxyquinolato) aluminum (Alq3) based organic light emitting diodes has been obviously improved by inserting a parylene-N (PPXN) buffer layer with proper thickness and location in the Alq3 layer. For an optimized PPXN inserted structure, current efficiency of 6.89 cd/A and luminous power efficiency of 1.85 lm/W were achieved; both are 42% higher than the 4.84 cd/A and 1.30 lm/W of the buffer free structure, respectively. The light emitting spectra of 4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran (DCM) doped Alq3 (Alq3:DCM) strips showed the electron current enhancement resulted in the observed efficiency improvement of PPXN inserted devices. The device current evolutions were explained by nonuniform potential distribution in the organic layer and the tunneling barrier reduction. [ABSTRACT FROM AUTHOR]

Resonant Raman spectroscopy studies of (Mn, Co)-codoped ZnO films were carried out using the 325 nm laser as the excitation source. The mixed mode character of the longitudinal optical (LO) phonon reveals that the resonant Raman spectra of the films can be used to test the c-axis orientation degree of their crystallite grains. The ratio of integrated Raman intensities between the 2LO to LO changes as a function of annealing temperatures, which reaches maximum at about 800 °C and demonstrates the variation of electron-LO phonon coupling in the films. These can provide helpful information for the fabrication of ZnO based functional films and for the development of their future applications. [ABSTRACT FROM AUTHOR]

Synchrotron radiation photoemission study showed that the energy level alignment at the interface between N, N'-bis(naphthalene-1-y1)-N, N'-bis(phenyl) benzidine (NPB), a typical hole transport material, and Al could be adjusted by precovering a thin C60 layer on Al. The interface dipoles so formed could shift both the highest occupied molecular orbital level of NPB and the secondary electron cutoff measured at the early stage of the NPB deposition. The barrier height for hole injection from Al to NPB could thus be lowered by as much as 0.98 eV, and the optimal thickness of the inserted C60 layer was found to be 8-12 Å. [ABSTRACT FROM AUTHOR]

Presents a study which examined the field dependence of magnetic transitions in magnetic superconductors. Discussion on the anisotropy of the magnetic transitions; Requirement for field-induced weak ferromagnetic transitions; Details of the experimental techniques used.

Presents a study which examined the systematic variation of anomalous praseodymium (Pr) antiferromagnetic ordering temperature for two-CuO[sub2]-layer cuprate systems. Details of the experimental techniques used; Discussion on the systematic of anomalous Pr ordering.