Evidence of a single nonmagnetic Co3+ state in the Na1 CoO2 cobaltate
Abstract
Macroscopic magnetization, muon spin rotation (μSR) , and NMR measurements were carried out to study magnetism in the Na1CoO2 cobaltate. Using superconducting quantum interference device measurements, Na1CoO2 is shown to have a bulk magnetic susceptibility much lower and flatter than that of NaxCoO2 with x=0.7-0.9 . In fact, μSR yields a signal of mostly nonmagnetic origin, which is attributed to the x=1 phase. The intrinsic cobalt spin susceptibility corresponding to this x=1 phase is measured using Na23 NMR. It is indeed found to be almost zero, in agreement with a low-spin 3+ charge state of all cobalt atoms. This single state of Co ions in CoO2 planes is confirmed by Co59 NMR, whose determination of cobalt shift and quadrupolar parameters allows us to give a reference value of the Co3+ orbital shift in cobaltates.
- Publication:
-
Physical Review B
- Pub Date:
- September 2005
- DOI:
- 10.1103/PhysRevB.72.094404
- arXiv:
- arXiv:cond-mat/0505668
- Bibcode:
- 2005PhRvB..72i4404L
- Keywords:
-
- 76.60.-k;
- 76.75.+i;
- 71.27.+a;
- 75.20.-g;
- Nuclear magnetic resonance and relaxation;
- Muon spin rotation and relaxation;
- Strongly correlated electron systems;
- heavy fermions;
- Diamagnetism paramagnetism and superparamagnetism;
- Strongly Correlated Electrons;
- Superconductivity
- E-Print:
- 7 pages, LaTeX