M. Forsthuber

Bio: M. Forsthuber is an academic researcher. The author has contributed to research in topics: Substitution (logic) & Electrical resistivity and conductivity. The author has an hindex of 1, co-authored 2 publications receiving 4 citations.

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.

Superconductivity of La2−ySryCu1−xNixO4+δ (y = 0.1, 0.2; 0⩽x⩽0.5) The hole-compensating effect of Ni

Abstract: Magnetization measurements below 50 K on ceramic La 2− y Sr y Cu 1− x Ni x O 4+ δ ( y = 0.1, 0.2; 0⩽ x ⩽0.5) show a progressive diminution of superconducting properties with increasing x . The larger suppressive action of Ni in the y =0.1 system than that for y =0.2 is attributed to the hole-compensating effect of Ni 3+ . The assumption that nickel is in the 3+ state satisfactorily explains: (1) the reduction in hole concentration, (2) a right-shift of the T c versus y curve with x , and (3) the low magnetic moment carried by Ni atoms, in the La 2−y Sr y Cu 1−x Ni x O 4+δ system.

Magnetic correlations and disorder in a two-dimensional fermi liquid: Possible important effects for high-Tc superconductors

Abstract: The influence of magnetic correlations and disorder in a two-dimensional Fermi liquid is considered in connection with the occurrence of the superconducting state. The disorder effect and magnetic correlations work against the superconducting state but at the same time are competitive phenomena. We show that the critical temperature can decrease due to the magnetic correlations and disorder, but the effect of correlations is reduced by the disorder. The electronic mass enhancement has been calculated taking into consideration the magnetic correlation effects and disorder. Its dependence on the concentration impurities, in agreement with the experimental data, shows the importance of the localization effects due to disorder. These results are in agreement with the experimental data obtained for the high critical temperature superconductors.

Effect on superconductivity of high valence ions V4+ and Ni3+ substitution for Cu site in Pr1.85Ce0.15CuO4−δ system

Abstract: Effects of high valence ions V 4+ and Ni 3+ substitution on superconductivity are studied systematically for the electron-doped superconducting Pr 1.85 Ce 0.15 CuO 4− δ (PCCO) system. The results indicate that very small amount of V 4+ substitution ( x ⩽ 0.04) for Cu 2+ site improves the superconductivity, but further substitution ( x ⩾ 0.06) will depress the superconductivity. Contrasting with V 4+ , Ni 3+ substitution shows a strong suppression on superconductivity, even for extremely small amount substitution of 0.01. Both the change of lattice parameters and the similar 3d electron structure of V 4+ ion to the Cu 2+ ion support the improvement of superconductivity while x ⩽ 0.04 in the V-substituted PCCO system. The results of Hall effect indicate that high valence ion substitution for Cu 2+ increase the carrier concentration, which is also one reason for the improvement of superconductivity of V 4+ substitution PCCO.

EFFECT OF Cu/Zn SUBSTITUTION UPON SUPERCONDUCTIVITY IN

Abstract: The phenomenon of high-Tc supercpnductivi 2ty in the two families of ceramic Cu-oxides CLaBaCuO , YBaCuO ) generated a wide spectrum of theoretical models which indicate that experimental data of these materials are of ~rime interest. According to recent bandstructure calculations ' 4 the main contribution to the density of states at the Fermi ~nelgy comes from the antibonding combinations of the Cu-dx -y - orbitals with the px- and py-orbi tals of the neighbouring 0- atoms. Therefore we substituted Cu by Zn whose ionic size and orbital structure is close to Cu and present results on the structural chemistry, electrical resistivity and heat capacity of well characterized samples.