Doping induced magnetic clusters and Co spin state transition in Na_xCoO_2 with 0.78<x<.97

C. Bernhard; Ch. Niedermayer; A. Drew; G. Khaliullin; S. Bayrakci; J. Strempfer; R. K. Kremer; D. P. Chen; C. T. Lin; B. Keimer

Doping induced magnetic clusters and Co spin state transition in Na_xCoO_2 with 0.78<x<.97

Superconductivity 2007-10-04 v2 Strongly Correlated Electrons

Authors: C. Bernhard , Ch. Niedermayer , A. Drew , G. Khaliullin , S. Bayrakci , J. Strempfer , R. K. Kremer , D. P. Chen , C. T. Lin , B. Keimer

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Abstract

By muon spin rotation we investigated the magnetic properties of a series of highly Na doped NaxCoO2 single crystals with 0.78(1)<x<0.97(1). Our data provide evidence for an intrinsically inhomogeneous magnetic state which can be described in tems of hole doping (Na vacancy) induced magnetic clusters that percolate at 1-x>0.04 until they yield a bulk magnetic state near x=0.78. Evidence for a strong (likely geometrical) frustration of the magnetic order is obtained from the anomalous doping dependence of the spin fluctuation rate (above the ordering temperature) which is strongly enhanced at x=0.78 as compared to x=0.97.

Keywords

sodium cobalt oxide magnetic clusters spin state transition muon spin rotation doping frustration

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@article{arxiv.cond-mat/0701033,
  title  = {Doping induced magnetic clusters and Co spin state transition in Na_xCoO_2 with 0.78<x<.97},
  author = {C. Bernhard and Ch. Niedermayer and A. Drew and G. Khaliullin and S. Bayrakci and J. Strempfer and R. K. Kremer and D. P. Chen and C. T. Lin and B. Keimer},
  journal= {arXiv preprint arXiv:cond-mat/0701033},
  year   = {2007}
}

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Doping induced magnetic clusters and Co spin state transition in Na_xCoO_2 with 0.78<x<.97

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