Antiferromagnetism in hydrated 123 compounds

TL;DR

This study reveals that hydration induces antiferromagnetic order in underdoped YBa₂Cu₃O₆.₅, with water insertion in CuO chains leading to magnetic phases detectable via NQR and ZFNMR.

Contribution

It demonstrates that water treatment in ambient conditions causes antiferromagnetic phases in 123 compounds, highlighting the role of CuO chains as water channels and detailing the magnetic properties.

Findings

Hydration induces antiferromagnetic order in YBa₂Cu₃O₆.₅.

Water insertion occurs via CuO chains, affecting magnetic phases.

Magnetic ordering persists even in epoxy-fixed powder samples.

Abstract

Copper nuclear quadrupole resonance (NQR) and zero field nuclear magnetic resonance (ZFNMR) studies of YBa$_2$Cu$_3$O$_{6.5}$ show that a magnetic phase appears in underdoped 123 superconductors treated in ambient wet air. The studies give convincing evidence that the ``empty'' CuO chains play the role of easy water insertion channels. The reaction occurs first in ordered regions of the crystallites. The final product of the reaction is a non-superconducting antiferromagnetic compound characterized by at least two types of magnetically ordered copper ions with ZFNMR spectra respectively in the frequency ranges of 46-96 and 96-135 MHz respectively. Even for powder samples fixed in an epoxy resin, the reaction is found to occur partly after a few years.