Complex magnetic differentiation of cobalts in Na${}_x$CoO${}_2$ with 22K Néel temperature

Abstract

Single crystals of sodium cobaltates Na${}_x$CoO${}_2$ with $x\approx 0.8$ were grown by the floating zone technique. Using electrochemical Na de-intercalation method we reduced the sodium content in the as-grown crystals down to pure phase with 22 K Néel temperature and $x\approx 0.77$. The ${}^{59}$Co NMR study in the paramagnetic state of the $T_N=22$ K phase permitted us to evidence that at least 6 Co sites are differentiated. They could be separated by their magnetic behaviour into three types: a single site with cobalt close to non-magnetic Co${}^{3+}$, two sites with the most magnetic cobalts in the system, and the remaining three sites displaying an intermediate behaviour. This unusual magnetic differentiation calls for more detailed NMR experiments on our well characterized samples.

arXiv comment5 pages, 4 figures, submitted to JETP Lett

References in corpus (10)

• Charge-ordering, commensurability and metallicity in the phase diagram of layered Na(x)CoO(2)
• Series of Bulk Magnetic Phase Transitions in NaxCoO2: a muSR study
• 59Co NMR study of the Co states in superconducting and anhydrous cobaltates
• NMR study of the magnetic and metal-insulator transitions in Na0.5CoO2: a nesting scenario
• Evidence of a single nonmagnetic Co3+ state in the Na1CoO2 cobaltate
• Spin correlations and cobalt charge states: A new phase diagram of sodium cobaltates
• Electronic texture of the thermoelectric oxide Na0.75CoO2
• Na ordering imprints a metallic kagome lattice onto the Co planes of Na2/3CoO2
• 59Co NMR evidence for charge and orbital order in the kagome like structure of Na2/3CoO2
• 23Na NMR study of sodium order in NaxCoO2 with 22K Neel temperature

Cited by in corpus (5)

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• Evolution of Co charge disproportionation with Na order in Na${}_x$CoO${}_2$
• Noncollinear and noncoplanar magnetic order in the extended Hubbard model on anisotropic triangular lattice
• Synthesis of sodium cobaltate Na${}_x$CoO${}_2$ single crystals with controlled Na ordering