Incommensurate magnetic structures of RMn6Sn6(R = Sc, Y, Lu) compounds from neutron diffraction study

In the present work, the influence of the substitution of Al for Mn on the structure and magnetic properties of TbMn6−xAlxSn6 compounds was investigated. With increasing Al concentration the lattice constants a, c, and the unit-cell volume V decrease monotonically. The TbMn6−xAlxSn6 compounds exhibit ferrimagnetic ordering. The magnetic ordering temperature first decreases with increasing Al content up to x=1.5, then increases with further increasing Al content. As for the unsubstituted material, it was found that this series of compounds exhibits a second magnetic transition at lower temperature that is attributed to spin reorientation. The spin-reorientation temperature and the magnetic anisotropy field first decrease with increasing Al content, go through a minimum at x=0.5, then increase with further increasing Al content. The saturation magnetization decreases monotonically with increasing Al content. Two metamagnetic transitions are found in TbMn6Sn6 compounds, one at 0.44 T, and the other at about ...

Structure and magnetic properties of TbMn6−xAlxSn6 compounds

Magnetic properties of DyMn6Ge6 studied by neutron diffraction and magnetic measurements

The magnetic and crystallographic properties of induction-melted SmMn/sub 6-x/Fe/sub x/Ge/sub 6/ compounds, where x is 0, 0.5, 1.0, and 1.5, have been studied using X-ray diffraction and bulk magnetic measurements between 30 and 490 K. All of the samples crystallized in the YCo/sub 6/Ge/sub 6/-type structure with the space group P6/mmm. A small amount, less than 9 mol%, of Sm(MnFe)/sub 2/Ge/sub 2/ was present as an impurity in all samples. The unit cell volume decreases with increasing iron content at an average rate of 2.4% per substituted atom at room temperature. The a and c lattice parameters decrease at an average rate of 1.1 and 0.1% per substituted atom at room temperature, respectively. The magnetic properties deteriorate rapidly as the iron concentration increases beyond x=0.5. Magnetic behavior of SmMn/sub 5/Fe/sub 1/Ge/sub 6/ and SmMn/sub 4.5/Fe/sub 1.5/Ge/sub 6/ is indicative of antiferromagnetic or ferrimagnetic coupling. According to X-ray diffraction patterns of magnetically aligned powders, the easy direction of magnetization at room temperature for all of the samples lies close to the basal plane of the unit cell.

Magnetic and crystallographic properties of SmMn/sub 6-x/Fe/sub x/Ge/sub 6/ intermetallics

A neutron diffraction study of the magnetic ordering of TmMn6Ge6

Magnetic properties of rare-earth manganese compounds of the RMn6Ge6 type

The possibility of fenimagnetic coupling between the magnetic moments of the light-rare-earth (Nd, Pr) ions and of the transition-metal (Fe) ions in NdrGa3Fe11- and Pr6Ga3Fe11-based compounds is deduced from the high-field magnetization curves measured at 4.2 K on magnetically aligned and on free-powder samples and from the temperature dependence of the magnetization. The ferrimagnetic coupling is very weak: at 4.2 K, the rare-earth moments and the transition-metal moments can be forced to ferromagnetic alignment by application of an external magnetic field of about 4 T. Generally, in intermetallic compounds, the magnetic coupling is ferromagnetic between light-rare-earth and transition-metal ions and ferrimagnetic between heavy-rare-earth and transition-metal ions. The present results suggest that in some crystal structures ferrimagnetic coupling also may exist in the compounds formed by light-rare-earth and transition-metal elements.

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V.H.M. Duijn

Papers

Magnetic properties of rare-earth manganese compounds of the RMn6Ge6 type

Possible ferrimagnetic coupling in light-rare-earth transition-metal intermetallic compounds