We use a combination of optical spectroscopy, first-principles calculations, and energy-dependent magneto-optical measurements to investigate the high-energy magnetodielectric effect in the frustrated kagome staircase compound Co3 V2 O8 and develop structure-property relations in this family of materials. The optical spectra show two distinct Co on-site d to d excitations that can be assigned as deriving from spine and cross-tie sites, respectively. The energy separation between these features is substantially larger in Co3 V2 O8 than in quasi-isostructural Ni3 V2 O8, indicating that the spine and cross-tie crystal field environments are more dissimilar in the Co compound compared with those in the Ni analog. Despite the similar appearance of the spectra, orbital correlation effects seem to dominate the optical properties of Co3 V2 O8, different from Ni3 V2 O8. Through the 6.2 K ferromagnetic transition temperature, Co3 V2 O8 displays ∼2% dielectric contrast near 1.5 eV, larger than that observed in the static dielectric constant. Co3 V2 O8 also shows a high-energy magnetodielectric contrast of ∼2% near 1.4 eV at 30 T, smaller than that of Ni3 V2 O8 (∼16% near 1.3 eV at 30 T). We attribute this result to the lack of strong lattice coupling at the low temperature magnetic phase boundaries.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Nov 7 2007|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics