Nature of optical properties of GdFe3(BO3)4 and GdFe2.1Ga0.9(BO3)4 crystals and other 3d5 antiferromagnetsA.V. Malakhovskii, A.L. Sukhachev, A.D. Vasil’ev, A.A. Leont’ev, A.V. Kartashev, V.L. Temerov and I.A. GudimEur. Phys. J. B, 85 2 (2012) 80DOI: https://doi.org/10.1140/epjb/e2012-20953-1