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Vanadium spinel oxides with formula $AV_2O_4$ (A = Fe, Co, etc.) have attracted much interest since they exhibit various intriguing physical properties, particularly in studying the role of orbital degrees of freedom in frustrated antiferromagnets [1,2]. However, very little attention has been paid to vanadium inverse spinel oxides $A_2VO_4$(A = Fe or Co). We report investigations on one of the inverse spinel oxides $Co_2VO_4$, where the spinal B-site has mixed occupancy by two distinct magnetic ions, $V^{4+}$ and low-spin $Co^{2+}$ . Our preliminary results show three distinct magnetic-phase transitions, among which a spontaneous magnetization reversal transition at 75 K, noncollinear and collinear magnetic transition at 140K and 168K, respectively. Here we report the results from polarized muon spectroscopy($\mu^+$SR) and thermodynamic characterizations, that have helped us in understanding unique physics of this complex system.
[1] P.G. Radaelli, New J. Phys. 7, 53, (2005).
[2]G. J. MacDougall et al. Phys. Rev. B 86, 060414(2012).
