Coexistence of superconductivity and antiferromagnetism in multilayered high-Tc superconductor HgBa2Ca4Cu5Oy: Cu-NMR study

We report a coexistence of superconductivity and antiferromagnetism in five-layered compound HgBa 2 (Ta 4 Cu 5 O y (Hg-1245) with T c = 108 K, which is composed of two types of CuO 2 planes in a unit cell; three inner planes(IP's) and two outer planes (OP's). The Cu-NMR study has revealed that the optimally doped OP undergoes a superconducting (SC) transition at T c = 108 K, whereas the three underdoped IP's do an antiferromagnetic (AF) transition below T N ∼60 K with the Cu moments of ∼(0.3-0.4)μ B . Thus bulk superconductivity with a high value of T c =108 K and a static AF ordering at T N =60 K are realized in the alternating AF and SC layers. The AF-spin polarization at the IP is found to induce the Cu moments of ∼0.02μ B at the SC OP, which is the AF proximity effect into the SC OP.