Structural, electronic and magnetic properties of Sc3+ doped CoCr2O4 nanoparticles

Abstract

The control over spin distribution to achieve magnetic properties in crystalline structures is crucial for materials design. A clear understanding of the relationship between structure and properties is essential for the development of magnetic materials. Herein, we investigate the effect of Sc-doping on the structural, electronic, and magnetic properties of Co_1−xSc_xCr₂O₄ (x = 0.0 and 0.05) nanoparticles synthesised by a solution combustion method and perform in-depth DFT calculations to clarify the spin distribution and magnetic states. The synthesized samples showed a single phase of the spinel cubic structure. Structural distortions associated with the creation of A-site vacancies originate from overall deformations of the tetrahedral [CoO₄] and octahedral [CrO₆] clusters. Aiming to understand the magnetic behavior of the sintered samples, temperature-dependent susceptibility and field-dependent magnetization studies were conducted, revealing two magnetic transitions defined as paramagnetic collinear ferrimagnetic (FIM) (T_C) and non-collinear spiral FIM (T_S) states. Further, upon Sc-doping of the [CoO₄] cluster, T_C and T_S decreased because of structural defects acting directly on the exchange coupling constants. The modification resulted in an enhancement of A–B and B–B antiferromagnetic (AFM) interactions, deeply clarified by DFT calculations. Hence, our experimental and theoretical approach uncovers a Sc-doping mechanism able to control the CoCr₂O₄ magnetic properties of the matrix using structural distortions and long-range spin ordering.