Structural, magnetic, magneto-dielectric and electronic structure study of Mn_1.5Cr_1.5O₄

Cr substituted Mn₃O₄ exhibited increased Néel temperature along with structural transition from tetragonally distorted Mn₃O₄ (x=0.00) to cubic Mn_1.5Cr_1.5O₄ (x=0.50). Mn_1.5Cr_1.5O₄ exhibits a dielectric anomaly around magnetic transition temperature which suggests that magneto-dielectric coupling is still present in this cubic system. Low-temperature X-ray diffraction pattern of Mn_1.5Cr_1.5O₄ at 20 K has confirmed the absence of structural transition below T_N. The observed magneto-dielectric effect in Mn_1.5Cr_1.5O₄ indicates that MD effect has been diminished in comparison to Mn₃O₄. X-ray photoemission spectra and X-ray absorption near-edge structure (XANES) confirms that Cr exists at the octahedral site with +3 oxidation state. Extended X-ray absorption fine structure (EXAFS) indicates increased short-range ordering in Mn_1.5Cr_1.5O₄ which could be a key factor for this increase in T_N.