Local structure distortions and mix valence effect on magnetic property of Cd-substituted CdCr2Se4

Abstract

CdCr2Se4 spinel system have been an interesting avenue for studying magnetic, resistive, and thermoelectric properties since they are strongly correlated to the crystal structure that is tunable by selection of charges and sizes of the A-site ions. Polycrystalline Cd1-xSbxCr2Se4 and Cd1-xInxCr2Se4 (x = 0, 0.05, 0.1) compounds were investigated by Cr K-edge EXAFS and Raman spectroscopy with an aim to understand the influence of local structure on the magnetic properties of these substituted compositions. EXAFS and Raman studies confirm the manifestation of mix valence state of Cr atom to maintain the charge balance in the substituted compounds. The formation of mix-valence Cr causes the difference in direct exchange coupling between 180°Cr3+/Cr2+ ions and indirect exchange interactions between 90°(Cr3+/Cr2+-Se-Cr3+/Cr2+) in the magnetic sub-lattice. © 2017 Author(s).