Spin Polarization of the Magnetic Spiral in Na Cu2 O2 as Seen by Nuclear Magnetic Resonance Spectroscopy

Abstract

The incommensurate (IC) spin ordering in quasi-one-dimensional edge-shared cuprate Na Cu2 O2 has been studied by Na23 nuclear magnetic resonance spectroscopy in an external magnetic field near 6 T applied along the main crystallographic axes. The NMR line shape evolution above and below TN ≈12 K yields a clear signature of an IC static modulation of the local magnetic field consistent with a Cu2+ spin spiral polarized in the bc plane rather than in the ab plane, as reported from earlier neutron diffraction data. © 2008 The American Physical Society.