Magnetic and specific heat data of the TmRhX (X = Ga, Ge) compounds are reported. These compounds crystallize in an orthorhombic crystal structure of the TiNiSi-type (space group Pnma). Magnetic data indicate that the compounds are antiferromagnets with the Néel temperature T_{N} equal to 3.9 K for TmRhGa and 6.0 K for TmRhGe. Magnetic susceptibility of TmRhGe has an additional peak at T_{t} = 10.6 K. In TmRhGe temperature dependence of χ"(T), the positions of both the peaks at T_{N} and T_{t} change with frequency indicating a relaxation process. These data suggest that with the decreasing temperature, first a cluster glass state and next the long-range aniferromagnetic order exists.
The magnetic properties including magnetic structure of poly and nano samples of TbMnO_{3} are determined. All the samples investigated are antiferromagnets. In these samples the Mn ad Tb moments order antiferromagnetically at different temperatures and form modulated magnetic structure described by the propagation vector k=(k_{x},0,0) with different value of k_{x} for the Mn and Tb sublattices. Comparison of the data for poly and nano samples indicates the decrease of the moment and increase of the k_{x} component of propagation vector in the nano specimens. The wide Bragg peak related to the Tb sublattice suggests that the magnetic order has the claster-like character. The magnetic moments value in both sublattices is smaller, whereas the k_{x} values are larger for nano samples.
In the work a brief discussion of the structural and magnetic properties of the manganites from the point of view of the micro- and macrostructures is presented. The influence of stoichiometry with the different oxygen parameter δ and doped atoms is discussed. The correlation between the crystal structure parameters and magnetic properties for some manganites is presented.
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