EXAFS Investigation of Ni2ScSbO6: Insights into Local Structure and Magnetodielectric Coupling

This proposal investigates Ni2ScSbO6, which features a spin-frustrated triangular lattice and spin-density wave (SDW) antiferromagnetic ordering below TN = 61 K, with a propagation vector of k = [0, 0.03575(1), 0]. Our research shows a strong, frequency-independent dielectric peak at TN, indicating significant magnetodielectric coupling and phonon softening in various Raman modes. Intriguingly, despite this dielectric anomaly, there is no ferroelectric polarization, suggesting that the peak may arise from subtle local structural changes, particularly within the NiO6 octahedra. Standard methods often miss these small structural variations, especially for lighter atoms like oxygen. To address this, we propose EXAFS and XANES measurements to provide insights into structural evolution near TN, focusing on valence states, ligand coordination, and local changes around Ni atoms, enhancing our understanding of magnetodielectric and spin-phonon coupling properties of this material.