Microwave absorption studies in new high-T<sub>c</sub> superconducting oxide systems: Tl-Ba-Ca-Cu-O and Bi-Ca-Sr-Cu-O
M D Sastry; R M Kadam; Y Babu; A G I Dalvi; I K Gopalakrishnan; P V P S S Sastry; G M Phatak; R M Iyer; M D Sastry; Chem. Group, Bhabha Atomic Res. Centre, Trombay, Bombay, India; R M Kadam; Chem. Group, Bhabha Atomic Res. Centre, Trombay, Bombay, India; Y Babu; Chem. Group, Bhabha Atomic Res. Centre, Trombay, Bombay, India; A G I Dalvi; Chem. Group, Bhabha Atomic Res. Centre, Trombay, Bombay, India; I K Gopalakrishnan; Chem. Group, Bhabha Atomic Res. Centre, Trombay, Bombay, India; P V P S S Sastry; Chem. Group, Bhabha Atomic Res. Centre, Trombay, Bombay, India; G M Phatak; Chem. Group, Bhabha Atomic Res. Centre, Trombay, Bombay, India; R M Iyer; Chem. Group, Bhabha Atomic Res. Centre, Trombay, Bombay, India
Журнал:
Journal of Physics C: Solid State Physics
Дата:
1988-06-10
Аннотация:
Microwave absorption studies of the new high-T<sub>c</sub> superconducting systems Tl-Ba-Ca-Cu-O (T<sub>c</sub>( rho =0)=118 K) and Bi-Ca-Sr-Cu-O (T<sub>c</sub>( rho =0)=84 K) were conducted using an X-band EPR spectrometer. The main features observed were (i) a sharp change in the leakage current at T<sub>c</sub>; (ii) intense low-field (<50 G) absorption below T<sub>c</sub>; and (iii) a largely field-independent absorption, the intensity of which was found to increase with increasing external magnetic field strength up to 10 kG. The dependence of the intensity on magnetic field is explained in terms of magnetic-field-induced decoupling of grains and field, and temperature-dependent lambda <sub>MW</sub>/ lambda , where lambda <sub>MW</sub> is the microwave penetration depth and lambda is the London penetration depth.
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