Anomalous magnetic reordering in magnetodielectric terbium iron garnet at low temperatures

摘要: Abstract The paper deals with five topics: i) the single three-dimensional irreductible representation (Г4g=T1g) of paramagnetic space group Ia 3 ¯ d No. 230 is chosen according to analysis Bertaut for interpretation neutron powder diffraction experiments performed on terbium iron garnet (Tb3Fe5O12); ii) use method “symmetry lowering device” in order select appropriate rhombohedral subgroup which allows deal case where cubic description provides an incomplete answer changes observed below 160 K ferrimagnetic structure around [1 1 1] axis from Neel model toward “double umbrella” at 13 K; iii) magnetic modes belonging one-dimensional A2g highest R c 167 are able describe occurrence its anisotropic character steeply increases due concomitant effects; iv) broad anomaly near 54 K temperature dependences components both sublattices Tb3+ ions Wyckoff positions (6e) and (6e′) explained partially basis concept Belov strong paraprocess has been termed “exchange-enhanced paramagnetism” so-called “low-temperature point” (TB); v) results related magnetodielectric effect low field significant coupling between exchange magnons ligand-field excitations reported recently this compound.