Date of Award


Degree Name

Master of Science




Harikrishnan S. Nair


In this thesis, we addressed the question of low dimensionality of trirutile compound CoTa2O6 and studied how the low dimensionality evolved with doping of Mg on Co-site. In order to study low dimensionality in CoTa2O6 and its derivative compounds Co1-xMgxTa2O6 (x = 0.1, 0.3, 0.5, 0.7, and 1), we used different techniques: X-ray diffraction, magnetic susceptibility, magnetization, specific heat and elastic neutron diffraction. We have addressed the question of low dimensional magnetism of CoTa2O6 by preparing phase-pure samples of the compound. In CoTa2O6 a broad feature is observed in magnetic susceptibility at 10 K and an antiferromagnetic phase transition is confirmed to occur at 6.2 K through magnetization, specific heat and neutron diffraction. It is noted that the transition peak at 6.2 K in the parent compound is robust up to 7 T and corresponds to an antiferromagnetic transition. With the addition of Mg, the peak at the magnetic transition is suppressed. Significant short-range spin fluctuations are present in CoTa2O6 as evidenced through specific heat analysis. The analysis of magnetic susceptibility combined with neutron diffraction data points towards a quasi-low-dimensional magnetic structure in CoTa2O6 which is suppressed with the addition of non-magnetic atom due to dilution of interaction between Co-atoms. Co1-xMgxTa2O6 with x > 0.5 show slight enhancement in ferromagnetism. Structural analysis using X-ray and neutron diffraction data shows anomalies in the lattice parameters corresponding to x = 0.5. Future studies will address the role of structure in observed magnetic features and the magnetic excitations in this trirutile compound series.




Received from ProQuest

File Size

58 pages

File Format


Rights Holder

Raju Baral