Uniform Mixing of Antiferromagnetism and High-Tc Superconductivity in Electron-doped Layers in Four-layered Ba2Ca3Cu4O8F2 : A New Phenomenon in an Electron Underdoped RegimePhenomenon in an Electron Underdoped Regime

TL;DR

This study reveals a novel coexistence of antiferromagnetism and high-temperature superconductivity in a four-layered cuprate, demonstrating self-doped electron and hole regimes with uniform mixing of these phases.

Contribution

It uncovers the simultaneous presence of AFM and HTSC in both electron- and hole-doped layers within a single four-layered cuprate, a new phenomenon in high-Tc superconductors.

Findings

AFM with TN=100 K coexists with superconductivity at 55 K.

Electrons transfer from inner to outer planes, confirming self-doped behavior.

Uniform mixing of AFM and HTSC occurs in both electron- and hole-doped layers.

Abstract

We report Cu- and F-NMR studies on a four-layered high-temperature superconductor Ba2Ca3Cu4O8F2(0234F(2.0)) with apical fluorine (F-1), an undoped 55 K-superconductor with a nominal Cu2+ valence on average. We reveal that this compound exhibits the antiferromagnetism (AFM) with a Neel temperature TN=100 K despite being a Tc= 55 K-superconductor. Through a comparison with a related tri-layered cuprate Ba2Ca2Cu3O6F2 (0223F(2.0)), it is demonstrated that electrons are transferred from the inner plane (IP) to the outer plane (OP) in 0234F(2.0) and 0223F(2.0), confirming the self-doped high-temperature superconductivity (HTSC) having electron and hole doping in a single compound. Remarlably, uniform mixing of AFM and HTSC takes place in both the electron-doped OPs and the hole-doped IPs in 0234F(2.0).