High-Tc Superconductivity with Tc = 52 K under Antiferromagnetic Order in Five-Layered Cuprate Ba2Ca4Cu5O10(F,O)2 with TN = 175 K: 19F- and Cu-NMR Studies

We report on the observation of high- T c superconductivity (SC) emerging with the background of an antiferromagnetic (AFM) order in the five-layered cuprate Ba 2 Ca 4 Cu 5 O 10 (F,O) 2 through 19 F-NMR and zero-field Cu-NMR studies. The measurements of spectrum and nuclear spin–lattice relaxation rates 19 (1/ T 1 ) of 19 F-NMR give convincing evidence for the AFM order taking place below T N = 175 K and for the onset of SC below T c = 52 K, hence both coexisting. The zero-field Cu-NMR study has revealed that AFM moments at Cu sites are 0.14 µ B at outer CuO 2 layers and 0.20 µ B at inner ones. We remark that an intimate coupling exists between the AFM state and the SC order parameter below T c = 52 K; the spin alignment in the AFM state is presumably changed in the SC-AFM mixed state.