Magnetic-Field-Induced Dielectric Anomalies in Cobalt-Containing Garnets.

Here we present a comparative study of the magnetic and crystal chemical properties of two Co 2+ containing garnets. CaY 2 Co 2 Ge 3 O 12 (which has been reported previously) and NaCa 2 Co 2 V 3 O 12 both exhibit the onset of antiferromagnetic order around 6 K as well as field-induced transitions around 7 and 10 T, respectively, that manifest as anomalies in the dielectric properties of the material. We perform detailed crystal-chemistry analyses and complementary density functional theory calculations to show that very minor changes in the local environment of the Co ions explain the differences in the two magnetic structures and their respective properties.