: A candidate system for purely oxygen antiferromagnet?

¹ Moscow State University - 119899, Moscow, Russia
² Ural State University - 620083, Ekaterinburg, Russia
³ Max Planck Institut für Chemische Physik Fester Stoffe D-01187, Dresden, Germany
⁴ Leibniz Institut für Festkörper- und Werkstofforschung Dresden D-01171, Dresden, Germany
⁵ TU-Clausthal, Institut für Mineralogie und Mineralische Rohstoffe D-38678, Clausthal-Zellerfeld, Germany

Received: 23 January 2003
Accepted: 18 May 2003

Abstract

Nuclear quadrupole resonance (-NQR) measurements in have revealed an unexpected puzzling picture evidencing the absence of a noticeable local hyperfine magnetic field on nuclei in the antiferromagnetically ordered state below , and considerable charge redistribution as compared with the counterpart system. Unconventional “nonmagnetic” behavior of copper ions in points to a possibly nonmagnetic copper valent state with antiferromagnetically ordered oxygen surroundings. It means that the hole in the cell should be localized at oxygen, rather than at copper sites. We suggest a qualitative physical reasoning for the “sp hybridization induced oxygen hole stabilization effect” which is believed to be more pronounced in as compared with .