Magnetic properties and magnetocaloric effect of Nd(Mn1−xFex)2Ge2 compounds

Polycrystalline Nd(Mn1−xFex)2Ge2 (0 ≤ x ≤ 1) compounds have been prepared by arc-melting. X-ray powder diffraction analysis shows that all samples crystallize in the ThCr2Si2-type structure with the space group I4/mmm. The substitution of Fe for Mn results in decreases of the lattice constants a, c and the unit-cell volume V. Magnetic properties and magnetocaloric effect of the compounds Nd(Mn0.9Fe0.1)2Ge2 and Nd(Mn0.8Fe0.2)2Ge2 have been studied by magnetic measurements. A spin reorientation transition at about 188 K is observed for Nd(Mn0.9Fe0.1)2Ge2. The Nd(Mn0.8Fe0.2)2Ge2 compound shows more complicated magnetic behavior, which is characterized by four magnetic ordering states below room temperature. The maximum values of the magnetic entropy change are 2.35 and 1.84 J kg−1 K−1 for x = 0.1 and 0.2, respectively, under the applied field changing from 0 to 5 T. The relative cooling powers of Nd(Mn0.9Fe0.1)2Ge2 and Nd(Mn0.8Fe0.2)2Ge2 are 145.9 and 133.8 J kg−1 under an applied field change of 5 T.