Magnetic order and superconductivity in RBa/sub 2/Cu/sub 3/O/sub z/
Moessbauer studies of /sup 57/Fe in RBa/sub 2-//sub y/K/sub y/(Cu/sub 1-//sub x/Fe/sub x/)/sub 3/O/sub z/, with R = Y and Pr, y = 0 and 0.5, x = 0.01, 0.05, and 0.1, z between 5.9 and 7.1, have been performed. A minority of the iron ions enter the Cu(2) site and reveal its magnetic order. For R = Y, y = 0, and x = 0.1, T/sub N/ equals 280 and 415 K for z = 6.5 and 6.1, respectively. The magnetic moments lie in the basal plane. In tetragonal, oxygen-rich PrBa/sub 2/(Cu/sub 0.9/Fe/sub 0.1/)/sub 3/O/sub 6.9/, T/sub N/ = 325 K; in superconducting YBa/sub 2/(Cu/sub 0.9/Fe/sub 0.1/)/sub 3/O/sub 7.1/ there is no magnetic order. In nonsuperconducting YBa/sub 1.5/K/sub 0.5/(Cu/sub 0.95/Fe/sub 0.05/)/sub 3/O/sub 6.1/ two distinctly inequivalent magnetic iron sites are observed, corresponding to iron in the Cu(2) site with different Ba-K neighbors. Moments of iron ions that have three Ba and one K as first nearest neighbors have a different temperature dependence and T/sub N/ (T/sub N/ = 450 K) from those with four Ba neighbors, where T/sub N/ = 415 K, showing that the antiferromagnetic exchange in the Cu(2) planes is strongly affected by the replacement of Ba/sup 2+/ by K/sup +/, probably by repelling oxygen from the Cu(2) plane. In superconducting YBa/sub 1.5/K/sub 0.5/(Cu/sub 0.95/Fe/sub 0.05/)/sub 3/O/sub 6.5/ the iron site with T/sub N/ = 450 K remains magnetic. The implications of these findings on the valencies of the Cu ions are discussed.
- Research Organization:
- Racah Institute of Physics, The Hebrew University, 91chemically bond904 Jerusalem, Israel
- OSTI ID:
- 6933767
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Vol. 38:10
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BARIUM OXIDES
MOESSBAUER EFFECT
SUPERCONDUCTIVITY
COPPER OXIDES
IRON OXIDES
POTASSIUM OXIDES
PRASEODYMIUM OXIDES
YTTRIUM OXIDES
HIGH TEMPERATURE
IRON 57
LOW TEMPERATURE
MAGNETIC MOMENTS
MEDIUM TEMPERATURE
TEMPERATURE DEPENDENCE
ULTRALOW TEMPERATURE
VALENCE
VERY LOW TEMPERATURE
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
IRON COMPOUNDS
IRON ISOTOPES
ISOTOPES
NUCLEI
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POTASSIUM COMPOUNDS
PRASEODYMIUM COMPOUNDS
RARE EARTH COMPOUNDS
STABLE ISOTOPES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties