S. Pöllinger

Bio: S. Pöllinger is an academic researcher from University of Vienna. The author has contributed to research in topics: Magnetoresistance & Superconductivity. The author has an hindex of 3, co-authored 4 publications receiving 20 citations.

The effect of Cu/Zn substitution in Nd1.85Ce0.15CuO4 on superconductivity studied by magnetic, transport and specific heat measurements and Raman spectroscopy

Abstract: We report on the structural chemistry, DC and AC magnetic, magnetoresistance, specific heat and Raman measurements of Cu/Zn substituted Nd 1.85 Ce 0.15 CuO 4 . Single phase solid solutions of Nd 1.85 Ce 0.15 Cu 1− x Zn x O 4− δ were observed for x ≤0.05 with the Nd 2 CuO 4 -type and with a random distribution of (Nd, Ce) and (Cu, Zn) on their respective lattice sites. Cu/Zn substitution suppresses superconductivity with an initial rate of −4.5 K/mol% Zn. With increasing x , the critical fields and critical current densities are strongly reduced whereas the number of effective pinning centers increases. The normal state electronic specific heat coefficient is estimated to be 11 mJ/(mol K 2 ). Anomalies of the resistivity and magnetoresistance are discussed in terms of a two-dimensional superconducting network in the perlocation regime. Raman spectroscopy indicates that with increasing Zn content the oxygen at the 4d site slightly displaced from the original position in the x − y plane.

The effect of Cu/M (M=Mn,Co,Ni,Zn) substitution upon superconductivity in Nd1.85Ce0.15CuO4

Abstract: The authors report on the structural chemistry, AC susceptibility, and resistivity measurements of Nd1.85Ce0.15(Cu1-xMx)O4 where Cu/M substitution reduces superconductivity with an initial rate of -4.5 K/mol.% Zn while 1% Co or Ni suppresses superconductivity below 4.2 K.

The influence of thermal treatments, fabrication methods and shapes on the magnetic transition of high temperature superconducting compounds

Abstract: We discuss the problem of characterizing a superconducting transition and the question of comparing samples originating from different fabrication processes and/or obtained under various shapes or morphologies (bulk, wires, thin films, single crystals, …). We present two different methods for the analyses of the AC susceptibility (for both the real and the imaginary part) in the low field limit. Strength of flux pinning and intergrain/intragrain contributions are discussed. Both analyses are applied to different inhomogeneous superconductors like high-Tc compounds (YBCO, LCO, LSCO, LBCO, B(P)SCCO, NCCO), Chevrel phases, etc. The dynamic critical field given by such an analysis allows an estimation of the quality and/or homogeneity of the superconducting sample and is a measure of the first intergrain (or Josephson) critical field.

Calorimetric study of the superconducting transition in Nd1.85Ce0.15CuO4−δ

Abstract: We report the first observation of a specific-heat anomaly at the superconducting transition temperature of high-quality Nd 1.85 Ce 0.15 CuO 4−δ ceramics with T c =24 K. The amplitude of the jump is ΔC / T c ≅6±0.5 mJ/mole K 2 . Application of a magnetic field H results in a broadening of the C p anomaly while the onset temperature remains field independent. We discuss the consistency of these results with previous magnetic and transport measurements.