Low dimensional magnetism in the trirutile tantalates Co1−xMgxTa2O6 with weak-ferromagnetic features

Abstract

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.