Magnetic and thermal properties of impurity doped high {Tc} superconductors
The magnetization and susceptibility of La{sub 2}Cu{sub 1-x}M{sub x}O{sub 4} with M = Zn and Ni (0 {<=} x {<=} 0.1) for temperature 1.8 {<=} T {<=} 400 K have been measured. The Neel temperatures of these compounds were determined and compared with the results from the zero-field muon-spin-rotation (ZF-{mu}SR) measurements. The antiferromagnetic order of La{sub 2}CuO{sub 4}, which is dependent on the applied field and very sensitive to the introduction of impurities creating mobile holes is less sensitive to the impurities which do not introduce mobile holes in the Cu-O{sub 2} planes. The Neel temperature (T{sub N}) is depressed rapidly with Zn-doping and the susceptibility peak becomes broadened and less well-defined with increasing x. These effects are less degree in Ni doped La{sub 2}CuO{sub 4}. The influence of these dopants on the metamagnetic behavior, which is concomitant with the antiferromagnetism in these systems, is studied. We have measured the thermal conductivity K(T) of polycrystalline YBa{sub 2}(Cu{sub 1-x}N{sub x}){sub 3}O{sub 7} with N = Zn and Al (0 {<=} x {<=} 0.1) and Y{sub 1-y}M{sub y}Ba{sub 2}Cu{sub 3}O{sub 7} with M = Pr and Gd (0 {<=} y {<=} 1.0) for temperatures 1.2 {<=} T {<=} 200 K. In the pure material, K(T) decreases slightly with decreasing temperature above T{sub c}, and below T{sub c} there is a strong enhancement of K(T) reaching a maximum at {approximately}50 K followed by sharp decrease. At temperature below 10 K, a T{sup 2} dependence for K(T) is evident and can be interpreted in terms of glass-like phonon scattering from the tunneling states within this system. Doping with Zn or Pr rapidly depresses T{sub c} and dramatically depresses the maximum in K(T) even for concentrations that remain superconducting. Comparisons between the K(T) behavior for the impurities that do not depress T{sub c} with those that diversely alter the superconducting properties and an analysis of the data using the Tewordt-Woelkhausen theory are shown.
- Research Organization:
- Temple Univ., Philadelphia, PA (United States)
- OSTI ID:
- 106822
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: 1993
- Country of Publication:
- United States
- Language:
- English
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