Microwave absorption and EPR studies of a new copper oxyfluoride superconductor synthesised through the ammonium bifluoride route
✍ Scribed by R.M. Kadam; B.N. Wani; M.D. Sastry; U.R.K. Rao
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 654 KB
- Volume
- 246
- Category
- Article
- ISSN
- 0921-4534
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✦ Synopsis
The recently reported superconductor Sr2CuO2F2. 4 is synthesised by a new route of fluorination by NH4HF 2 and its superconducting phase is investigated by electron paramagnetic resonance, direct microwave absorption and non-resonant response employing magnetic field modulated microwave absorption. These studies have given clear evidence for the occurrence of a superconducting phase below 40 K. From the magnetic field dependence of the changes in microwave absorption, the lower critical field Hcl (perpendicular to the c-axis) is determined to be 100 G at 10 K. The EPR studies on this oxyfluoride have shown a Cu 2+ signal with 19F super hyperfine structure due to interaction with two equivalent F nuclei. In view of its low intensity it was assigned to a possible 'defect site' in the lattice. The line width of the EPR signal increased in the superconducting phase smearing out the 19F shfs below 35 K. This is consistent with what is normally expected in superconductors.