The magnetic properties of the low-dimensional trirutile tantalates Co1−xMgxTa2O6 [x = 0.0, 0.1, 0.3, 0.5, 0.7, 1.0] are reported in this paper. CoTa2O6 is an antiferromagnet with a transition temperature at TN=6.6 K, while showing a very broad peak in the magnetic susceptibility at ≈12 K owing to the low dimensionality of the magnetic interactions. In our study, where Mg is introduced at the Co position, we see the disappearance of the broad transition for high values of x. For the x=0.1 composition, three transitions are observed in the magnetization at 28 K, 6 K, and 3.3 K. Our analysis of magnetization data using the anisotropic Heisenberg and the Ising models for spin chains points out that the magnetic interactions in Co1−xMgxTa2O6 are indeed low dimensional. Field-induced metamagnetic transitions are observed in the case of x=0 and x=0.1 compositions of Co1−xMgxTa2O6, which are evident in the magnetization isotherms at T=2 K. Interestingly, we find that with progressive doping up to x=0.5 and 0.7, we obtain higher magnetization pointing to the possibility of weak-ferromagnetism. This might point toward the formation of single-chain magnets, which opens up a new possibility in low dimensional oxides for spintronics applications.
4 1 4 0). Upon Mg-dilution at x ≥0.1, the long-range ordered magnetism is destroyed. The present results should motivate an investigation of magnetic excitations in this low-dimensional anisotropic magnet. PACS numbers: Recent investigation on CoTa 2 O 6 has revealed optical dichroism in the single crystals 17 . The dichroism was attributed to the anisotropic exchange mechanism related to the M -O-O-M chains. In addition to the low-dimensionality and anisotropic exchange, the specific heat of CoTa 2 O 6 presented evidence for a large fraction of spins of Co remain-FIG. 1: (color online) The crystal structure of CoTa2O6. (a) The Co atoms represented by blue spheres forms CoO6 octahedra with the oxygen atoms (in red). (b) Shows a projection on to the ab-plane from which the square planar arrangement of Co can be seen. The figures were created using xfplo version of FPLO 16 .
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