Comparative Raman scattering study of crystal field excitations in Co-based quantum magnets
Banasree S. Mou, Xinshu Zhang, Li Xiang, Yuanyuan Xu, Ruidan Zhong, R. J. Cava, Haidong Zhou, Zhigang Jiang, Dmitry Smirnov, Natalia Drichko, Stephen M. Winter
Abstract
Co-based materials have recently been explored because of their potential to realize complex bond-dependent anisotropic magnetism. Prominent examples include ${\mathrm{Na}}_{2}{\mathrm{Co}}_{2}{\mathrm{TeO}}_{6}, {\mathrm{BaCo}}_{2}{({\mathrm{AsO}}_{4})}_{2}, {\mathrm{Na}}_{2}\mathrm{BaCo}{({\mathrm{PO}}_{4})}_{2}$, and ${\mathrm{Co}\mathit{X}}_{2}$ $(X=\mathrm{Cl},\mathrm{Br},\mathrm{I})$. In order to provide insight into the magnetic interactions in these compounds, we make a comparative analysis of their local crystal electric field excitations spectra via Raman scattering measurements. Combining these measurements with theoretical analysis confirms the validity of ${j}_{\mathrm{eff}}=1/2$ single-ion ground states for all compounds, and provides accurate experimental estimates of the local crystal distortions, which play a prominent role in the magnetic couplings between spin-orbital coupled Co moments.