Transport, magnetic and structural properties of Mott insulator MnV2O4 at the boundary between localized and itinerant electron limit
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The effect of Zn and Cr doping on the transport and magnetic properties of MnV2O4 have been investigated using resistivity, thermoelectric power (TEP), magnetization, neutron diffraction and X-ray diffraction techniques. It is observed, that with increase in Zn substitution the non-collinear orientation of Mn spins with the V spins decreases which effectively leads to the decrease of structural transition temperature more rapidly than Curie temperature. Investigations also show that with Zn doping both the Curie temperature (T C) and structural transition temperature (T S) decrease, while the gap between them increases rapidly. On the other hand, with Cr doping on the V site the T C remains almost constant but T S decreases rapidly. Moreover, with Zn doping both resistivity and TEP decrease, whereas with 10 % Cr doping the TEP decreases and a change of sign occurs indicating an increase in the band gap. This leads to the decrease of the mobility of the polaronic holes than the mobility of the electronic polarons at low temperature.
KeywordsMott Insulator Zero Field Cool Orbital Degeneracy Homopolar Bonding Polaronic Hole
SC is grateful to the funding agencies DST (Grant No: SR/S2/CMP-26/2008) and CSIR (Grant No: 03(1142)/09/EMR-II) for financial support. PS is grateful to CSIR, India for providing research fellowship. Authors are also grateful to D. Budhikot for his help in magnetization measurement.
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