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Low‐Temperature Dependence of the EPR Spectra of Gd 0.5 RE 0.5 Ba 2 Cu 3 O 7−δ Compounds in the Tetragonal Phase
Author(s) -
Guskos N.,
Likodimos V.,
Londos C. A.,
Windsch W.,
Metz H.,
Koufoudakis A.,
Mitros C.,
GamariSeale H.,
Niarchos D.
Publication year - 1992
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221700225
Subject(s) - tetragonal crystal system , orthorhombic crystal system , analytical chemistry (journal) , atmospheric temperature range , ion , electron paramagnetic resonance , phase (matter) , materials science , spectral line , perovskite (structure) , nuclear magnetic resonance , crystallography , chemistry , crystal structure , physics , organic chemistry , chromatography , meteorology , astronomy
The EPR spectra of perovskite ceramics of Gd 0.5 RE 0.5 Ba 2 Cu 3 O 7−δ type (RE La, Pr, Nd, Sm, Eu, Dy, Ho, Y, Er, Tm, Yb, and Lu) in tetragonal (non‐HTC) phase are investigated as a function of temperature in the range 40 to 3 K. A signal arising from the isotropic exchange interaction of coupled pairs of Cu 2+ ions is detected. The intensity of this signal is strongly dependent on the RE ions and its g ‐factor varies with temperature. Magnetic measurements show the existence of ferromagnetic anomalies at these low temperature. In the orthorhombic phase, these materials exhibit a superconducting phase transition in the range of 85 to 95 K, apart from the samples with La ions where a T C ≈ 69 K is found and the samples with Prions where a superconducting state can not be observed.