R sublattice

Hydrogenation does not practically change the exchange field h22 within the R - sublattice. 

Crystallographic and magnetic data of some selected ternary R-Fe-B compounds. Top part stable compounds. Bottom part metastable compounds. For more details, see main text. The lattice constant c of R1+EFe4B4 refers to the R-sublattice, the corresponding value of the Fe sublattice is given between parentheses, the quantity e for each compound can be obtained by using the relation e = cFe/cR — 1. 

A different method for estimating /RFe was used by Hirosawa et al. (1986). These authors fitted their experimental data of the reduced R sublattice magnetization Mr(T)/Mr(0) by means of a Brillouin function ... 

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. 

Nevertheless, the total anisotropy of the ThMni2-type compounds result from the contributions of both magnetic-rare-earth and 3d-transition-metal sublattices. The anisotropy of the R sublattice is mostly determined by the crystal-field (CEF) interactions whereas the anisotropy of the transition-metal sublattice is due to anisotropy of exchange interactions. The Hamiltonian for the 4f-3d compounds (see e.g. Stefans and Wrzeciono 1989)is... 

ND, crystallographic positions and atomic parameters c is easy axis at RT, 50.2 angle between easy axis and c at 4.2 K R-sublattice anisotropy prevails = 170K, rfR >300K CEF parameters rsR, = 198K, 7 srj = 211K... 

B BLi T spins external magnetic field (n H) effective molecular field acting on M A/r sublattice magnetization magnetization of the R sublattice... 

Curves of the M T) dependence for RCo3Sn show a ferrimagnetic ordering of the Co and R sublattices, which is characteristic of the intermetallic compounds of the heavy rare earths with Co. For GdCoaSn the magnetic moment of Gd (6.1/ub) has been obtained by an extrapolation of the M T) curves to OK. 

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