Cu and F NMR studies on four-layered cuprates Ba2Ca3Cu4O8(O1−yFy)2

We report on a possible onset of magnetism in F-substituted four-layered high- T c compounds Ba 2 Ca 3 Cu 4 O 8 (O 1− y F y ) 2 (2 y = 1.2, 1.4, 1.6 and 2.0) which are composed of two types of CuO 2 planes in a unit cell; two inner planes (IP’s) and two outer planes (OP’s). The Cu NMR study has revealed that the hole density at the OP’s is slightly larger than that at the IP’s, and a total carrier density decreases as F content increases. The F NMR study has probed the antiferromagnetic order below T N ≃ 100 K in 0234F(2.0) which undergoes a superconducting transition below T c = 55 K. This result gives evidence for the coexistence of antiferromagnetism and superconductivity even in four-layered high- T c cuprates as well as for five-layered Hg-based multilayered high- T c cuprates.