High-T_c Superconductivity with T_c = 52 K under Antiferromagnetic Order in Five-layered Cuprate Ba_2Ca_4Cu_5O_10(F,O)_2 with T_N = 175 K: 19F- and Cu-NMR Studies

TL;DR

This study demonstrates the coexistence of high-temperature superconductivity at 52 K with antiferromagnetic order at 175 K in a five-layer cuprate, using 19F- and Cu-NMR techniques to reveal detailed magnetic and superconducting properties.

Contribution

It provides new insights into the coexistence and interplay of antiferromagnetism and superconductivity in layered cuprates through NMR studies.

Findings

Antiferromagnetic order exists below 175 K.

Superconductivity emerges below 52 K.

AFM moments are 0.14 and 0.20 mu_B at different Cu sites.

Abstract

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_2Ca_4Cu_5O_10(F,O)_2 through 19F-NMR and zero-field Cu-NMR studies. The measurements of spectrum and nuclear spin-lattice relaxation rates 19(1/T_1) of 19F-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 mu_B at outer CuO_2 layers and 0.20 mu_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.