Symmetry analysis of the magnetic structures in TbIG and Tb:YIG at low temperature

Temperature Evolution of the Double Umbrella Magnetic Structure in Terbium Iron Garnet

“…12a). These results are in good agreement with our recent high magnetic field magnetizations performed at 4.2 K (Lahoubi, 2012) where a third low critical field H c0 (Fig. 13) is observed along the <100> direction and added to the previous H c1 and H c2 .…”

“…In addition to the earlier reflections (hkl) observed previously, pure superstructure lines (hkl) * forbidden by the nuclear space group Ia 3 d are present and we have I = I M (hkl) * : (110) * , (310) * , (411, 330) * , (433, 530) * and (510) * . In contrast to previous findings at 1.5 K (Bertaut et al, 1970;Tchéou al., 1970a) and 4.2 K , the small superstructure lines (200)* and (600, 442)* have been observed recently and confirmed only at 5 K (D1B) (Lahoubi, 2012) with a sensibility equal to 0.5 and 1% respectively, the line (110)* being chosen as a reference. The same order of magnitude (1/276) by comparison with the previous result (Hock et al, 1990) was found for the line (200)*.…”

“…Four rhombohedral models in A 2g of R 3 c and new model for TbIG (Lahoubi, 2012) The second part ( a g j ) represents the non collinear antiferromagnetic modes of the components of the moment m j along the three rhombohedral axes { (Fig. 11a).…”

“…At low temperature when both crystal field acting on the RE 3+ ions and the RE 3+ {c}-Fe 3+ (d) magnetic exchange anisotropies become important (Nekvasil & Veltrusky, 1990), the Néel model must be replaced by a new spin configuration in which the RE 3+ magnetic moments cease to be antiparallel to the Fe 3+ magnetization M Fe . So, neutron diffraction experiments have been performed previously to study, the non collinear magnetic structures of the RE 3+ moments (RE = Dy, Er, Ho, Tb, Tm and Yb) which appear at liquid-helium temperatures (Bertaut et al, 1970;Guillot et al, 1982;Herpin et al, 1960;Hock et al, 1990Hock et al, , 1991Lahoubi, 1986Lahoubi, , 2012Pickart et al, 1970;Tchéou et al, 1970aTchéou et al, , 1970b. Neutron diffractions experiments have been also made to follow the temperature dependence of these ''umbrella'' magnetic structures in HoIG (Guillot et al, 1983, ErIG (Hock et al, 1991), DyIG (Lahoubi et al, 2009(Lahoubi et al, , 2010.…”

“…In the present chapter, we will present the temperature evolution of the Tb 3+ magnetic ordering in TbIG using powder neutron diffraction experiments combined with magnetic field magnetization measurements on single crystal (Lahoubi et al, , 1985Lahoubi, 1986;Lahoubi et al, 1997;Lahoubi, 2012). The experimental techniques are described in the section 2.…”