High-resolution spectroscopy, crystal-field calculations, and quadrupole helix chirality of DyFe3(BO3)4

High-resolution polarized transmission spectra of DyFe 3 (BO 3 ) 4 single crystals were investigated in broad spectral (10-23000 cm −1 ) and temperature (3.5-300 K) ranges. Energies of the dysprosium levels in the paramagnetic and antiferromagnetic phases were determined. On the basis of these data and preliminary calculations in the frameworks of the exchange-charge model, we determined the crystal-field and Dy-Fe exchange interaction parameters of the Dy 3 + ions at sites with the point C 2 symmetry corresponding to the enantiomorphic P 3 1 21 and P 3 2 21 space groups. The values of electronic quadrupole moments of the Dy 3+ ions were calculated, which enabled us to interpret results of the work [Usui et al., Nature Mater. 13, 611 (2014)] on the observation of domains of different quadrupole chirality in DyFe 3 (BO 3 ) 4 .