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Frequency dependent losses in REBa 2 Cu 3 O 7 (RE = Dy, Ce)
Author(s) -
Roy D.,
Deb S. K.,
Neogy C.,
Nag A.
Publication year - 1994
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.2221830218
Subject(s) - superconductivity , meissner effect , polaron , condensed matter physics , quantum tunnelling , thermal conduction , materials science , analytical chemistry (journal) , phase (matter) , volume fraction , relaxation (psychology) , nuclear magnetic resonance , physics , chemistry , psychology , social psychology , chromatography , quantum mechanics , composite material , electron
Frequency dependent response of DyBa 2 Cu 3 O 7 and CeBa 2 Cu 3 O 7− x is measured by a simple contactless method over a wide frequency range (1 KHz to 13 MHz) at 300 and 77 K. The volume fraction of the superconducting phase can be easily estimated by the method. It is seen that χ′ (≈ −1/4π × Meissner fraction) for DyBa 2 Cu 3 O 7 at 77 K is independent of frequency up to 10 MHz in the Meissner state. For CeBa 2 Cu 3 O 7− x which is a non‐superconducting insulator, χ′ is positive and increases with frequency both at 300 and 77 K (χ′ (77 K) < χ′ (300 K)). The relaxation mechanism for the ac conduction in DyBa 2 Cu 3 O 7 in the normal state is suggested to be primarily due to tunnelling and hopping of 2p hole polarons located at oxygen sites.