Abstract
In the high-temperature superconductors of the type YBa{sub 2}Cu{sub 3}O{sub x}, YBa{sub 2}Cu{sub 4}O{sub 8} and YBa{sub 2}Cu{sub 3.5}O{sub 15} the Y-ion in between the superconducting planes can be substituted by most of the rare earth ions without changing the superconducting properties, whereas the electron superconductors Nd{sub 2}Cu and Pr{sub 2}CuO{sub 4} alredy contain rare earth ion. The crystalline electric field of the plane oxygen and copper splits the (2J+1)-fold degeneracy of the magnetic ground state of the rare earth ion into different levels. This CEF-splitting can directly be measured by inelastic neutron scattering. Therefore the rare earth ion is a local probe of the structure and the charges in the superconducting planes. By varying sample parameters as oxygen stoichiometry or doping the CEF-splitting turned out to be very sensitive to structural and electronic changes. Taking into account both structure and CEF data quantitative results of the charge associated with doping or oxygen variation can be derived, if the quality of the data is sufficient. J-mixing and intermediate coupling had to be included in the analysis of the CEF-splitting of Nd{sub 1+y}Ca{sub v}Ba{sub 2-y-v}Cu{sub 3+z}O{sub x}. A small decrease of the oxygen concentration turned out to induce a small amount
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Citation Formats
Allenspach, P.
Neutron spectroscopic investigation of high temperature superconductors; Neutronenspektroskopische Untersuchung von Hochtemperatursupraleitern.
Switzerland: N. p.,
1991.
Web.
Allenspach, P.
Neutron spectroscopic investigation of high temperature superconductors; Neutronenspektroskopische Untersuchung von Hochtemperatursupraleitern.
Switzerland.
Allenspach, P.
1991.
"Neutron spectroscopic investigation of high temperature superconductors; Neutronenspektroskopische Untersuchung von Hochtemperatursupraleitern."
Switzerland.
@misc{etde_10113962,
title = {Neutron spectroscopic investigation of high temperature superconductors; Neutronenspektroskopische Untersuchung von Hochtemperatursupraleitern}
author = {Allenspach, P}
abstractNote = {In the high-temperature superconductors of the type YBa{sub 2}Cu{sub 3}O{sub x}, YBa{sub 2}Cu{sub 4}O{sub 8} and YBa{sub 2}Cu{sub 3.5}O{sub 15} the Y-ion in between the superconducting planes can be substituted by most of the rare earth ions without changing the superconducting properties, whereas the electron superconductors Nd{sub 2}Cu and Pr{sub 2}CuO{sub 4} alredy contain rare earth ion. The crystalline electric field of the plane oxygen and copper splits the (2J+1)-fold degeneracy of the magnetic ground state of the rare earth ion into different levels. This CEF-splitting can directly be measured by inelastic neutron scattering. Therefore the rare earth ion is a local probe of the structure and the charges in the superconducting planes. By varying sample parameters as oxygen stoichiometry or doping the CEF-splitting turned out to be very sensitive to structural and electronic changes. Taking into account both structure and CEF data quantitative results of the charge associated with doping or oxygen variation can be derived, if the quality of the data is sufficient. J-mixing and intermediate coupling had to be included in the analysis of the CEF-splitting of Nd{sub 1+y}Ca{sub v}Ba{sub 2-y-v}Cu{sub 3+z}O{sub x}. A small decrease of the oxygen concentration turned out to induce a small amount of negative charge into the superconducting planes, whereas simultaneously T{sub c} decreases very rapidly. Alreay 0.03 `e/plane oxygen` is needed. The origin of this behavior is the rather weak stability of NdBa{sub 2}Cu{sub 3}O{sub x} displayed as well in the tendency towards O5-occupation. Doping of additional Nd onto the Ba site or Ca yields additional negative or positive charge on the plane oxygen, respectively. CEF-calculations of the charge variation are consistent with the values obtained by other methods (e.g. Hall effect). (author) figs., tabs., 108 refs.}
place = {Switzerland}
year = {1991}
month = {Dec}
}
title = {Neutron spectroscopic investigation of high temperature superconductors; Neutronenspektroskopische Untersuchung von Hochtemperatursupraleitern}
author = {Allenspach, P}
abstractNote = {In the high-temperature superconductors of the type YBa{sub 2}Cu{sub 3}O{sub x}, YBa{sub 2}Cu{sub 4}O{sub 8} and YBa{sub 2}Cu{sub 3.5}O{sub 15} the Y-ion in between the superconducting planes can be substituted by most of the rare earth ions without changing the superconducting properties, whereas the electron superconductors Nd{sub 2}Cu and Pr{sub 2}CuO{sub 4} alredy contain rare earth ion. The crystalline electric field of the plane oxygen and copper splits the (2J+1)-fold degeneracy of the magnetic ground state of the rare earth ion into different levels. This CEF-splitting can directly be measured by inelastic neutron scattering. Therefore the rare earth ion is a local probe of the structure and the charges in the superconducting planes. By varying sample parameters as oxygen stoichiometry or doping the CEF-splitting turned out to be very sensitive to structural and electronic changes. Taking into account both structure and CEF data quantitative results of the charge associated with doping or oxygen variation can be derived, if the quality of the data is sufficient. J-mixing and intermediate coupling had to be included in the analysis of the CEF-splitting of Nd{sub 1+y}Ca{sub v}Ba{sub 2-y-v}Cu{sub 3+z}O{sub x}. A small decrease of the oxygen concentration turned out to induce a small amount of negative charge into the superconducting planes, whereas simultaneously T{sub c} decreases very rapidly. Alreay 0.03 `e/plane oxygen` is needed. The origin of this behavior is the rather weak stability of NdBa{sub 2}Cu{sub 3}O{sub x} displayed as well in the tendency towards O5-occupation. Doping of additional Nd onto the Ba site or Ca yields additional negative or positive charge on the plane oxygen, respectively. CEF-calculations of the charge variation are consistent with the values obtained by other methods (e.g. Hall effect). (author) figs., tabs., 108 refs.}
place = {Switzerland}
year = {1991}
month = {Dec}
}