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Coexistence of Superconductivity and Antiferromagnetism in Multilayered High-$T_c$ Superconductor HgBa$_2$Ca$_4$Cu$_5$O$_y$: A Cu-NMR Study

H. Kotegawa·Y. Tokunaga·Y. Araki·G. -q. Zheng·Y. Kitaoka·K. Tokiwa·K. Ito·T. Watanabe·A. Iyo·Y. Tanaka·H. Ihara
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Abstract

We report a coexistence of superconductivity and antiferromagnetism in five-layered compound HgBa$_2$Ca$_4$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 optimallydoped OP undergoes a superconducting (SC) transition at $T_c=108$ K, whereas the three underdoped IP's do an antiferromagnetic (AF) transition below $T_N\sim$ 60 K with the Cu moments of $\sim (0.3-0.4)μ_B$. 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 $\sim0.02μ_B$ at the SC OP, which is the AF proximity effect into the SC OP.

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H. Kotegawa, Y. Tokunaga, Y. Araki, G. -q. Zheng, Y. Kitaoka, K. Tokiwa, K. Ito, T. Watanabe, A. Iyo, Y. Tanaka, H. Ihara. 2004-01-22. Coexistence of Superconductivity and Antiferromagnetism in Multilayered High-$T_c$ Superconductor HgBa$_2$Ca$_4$Cu$_5$O$_y$: A Cu-NMR Study. https://doi.org/10.1103/physrevb.69.014501

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