Spin reorientation transition

Ivanova, T.I., Pastushenkov, Yu.G., Skokov, K.P., Telegina, I.V., Tskhadadze, I.A. (1998) Spin-reorientation transitions and magnetic anisotropy in TbFen-xCoxTi compounds, J.Alloys Comp. 280 20-25. 

The intrinsic magnetic properties of the Er2Fei4B intermetallic compound have been previously investigated [1], According to the literature data [1,2] the magnetic ordering temperature of this compound is Tc = 554 K. Er2Fei4B exhibits one successive spin reorientation transition (SRT) at about 325 - 327 K. 

The aim of this work is to study the effect of hydrogenation on the magnetic phase transitions (Curie and spin-reorientation transition temperatures) in the Er2Fei4B compound using the magnetization measurements with continuous control of the hydrogen content in the examined sample. 

Figure 3. The dependence of spin-reorientation transition temperature on the hydrogen pressure for Er2Fei4BHx.

The spin-reorientation transition in Er2Fei4B compound can be attributed to the competing of the uniaxial Fe sub lattice and the planar rare-earth sublattice anisotropy, with the former being dominant at higher temperatures and the latter being dominant at lower ones. 

SR TIP spin reorientation transition (temperature) temperature-independent paramagnetism X magnetic susceptibility... 

Fig. 34. (Upper panel) lattice parameters (a circles, right-hand scale c triangles, left-hand scale) and (lower panel) Curie (Tq) and spin-reorientation (Tgg) temperatures (left-hand scale, circles), and saturation trragnetization M, at 290 K (right-hand scale, crosses) versus Co concentration x in DyFeu Co Vj alloys. Note that there are two spin-reorientation transitions below RT. The surprisirtg spin-reorientation phenorttena in DyCO oV2 [shown here by 7 s ( )] results from an M(T) plot near 615 K (see fig. 32). At present one carmot determine the phase which is formed at this temperature. (Jurczyk et al. 1991a,b.)...

The ThMni2 tetragonal structure (axial) causes anisotropy in the reported compounds. The anisotropy, particularly at low temperature, results predominantly from the lanthanide (R) sublattice however, as mentioned above it has recently been acknowledged that there is also a substantial contribution from the transition-metal sublattice (Thuy 1994, private communication). The interplay of anisotropy of both sublattices gives the final shape of the total anisotropy and causes the interesting phenomenon of the spin-reorientation transition to be discussed in sect. 3.3.3. 

The theoretical discussions applied to the explanation of magnetic behavior of the ThMni2-type compounds can be easily divided into two groups. The first group is based on the combination of the CEF (in point-charge approximation) and molecular-field approximation (MFA) models and has had considerable success in consideration of the anisotropy, spin-reorientation transitions, and the temperature and field dependences of the magnetic parameters. 

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