Abstract
We present an extensive microscopic magnetic study of the quasi-one-dimensional frustrated spin-chain compound linarite. Angular-dependent susceptibility and -NMR measurements were performed at various temperatures in the paramagnetic state. All relevant NMR parameters, viz., the chemical, the dipolar, and the Fermi-contact contribution, were extracted to analytically calculate the local magnetic fields at the sites. From this analysis, a significant spin transfer of % from the magnetic copper ions onto the two oxygen ligands was derived. This result is compared to LSDA+ calculations, which further can explain the significant reduction of the coupling constants of the compound compared to other edge-sharing CuO chains due to the presence of specific OH bonds in linarite. The magnetically ordered spin-spiral ground state for K was investigated by -NMR for fields T along the three crystallographic main directions. With the derived NMR parameters in the paramagnetic regime it is possible to model the NMR spectrum of the magnetically ordered state for . A deviation observed between the NMR data and the evaluated spectrum for is discussed in terms of a significant rearrangement of the spiral state in an applied field of T for this direction.
5 More- Received 18 July 2014
- Revised 13 November 2014
DOI:https://doi.org/10.1103/PhysRevB.90.224417
©2014 American Physical Society