High-pressure spectroscopic investigation of multiferroic Ni3TeO6

We combined diamond anvil cell techniques, infrared and Raman spectroscopies, and lattice dynamics calculations to explore the high pressure properties of multiferroic Ni3TeO6. Using a frequency trend analysis, we trace a subtle decrease in compressibility near 4 GPa to a minimum in the O-Ni2-O bond angle. This unique behavior emanates from the proximity of the Ni2 center in the Ni3-Ni2-Ni1-Te chain to a flexible pocket that is intrinsic to the crystal structure. At the same time, predicted trends in the superexchange pathways are consistent with greater antiferromagnetic character under compression, in line with both phase stability calculations and direct susceptibility measurements. These findings highlight opportunities for local structure control of corundumlike materials.