Magnetism and magnetoresistance of Dy1−xSmxMn6Ge6 (x = 0.2–1.0) compounds

Abstract

The magnetic and transport properties of Dy1−xSmxMn6Ge6 (x = 0.2–1.0) have been investigated using x-ray diffraction (XRD) and magnetization measurements. Analysis of the XRD patterns indicates that the samples with x ⩽ 0.4 mainly consist of the HfFe6Ge6-type phase and the samples with 0.6 ⩽ x ⩽ 1.0 mainly consist of the YCo6Ge6-type phase (P6/mmm). The lattice constants and the unit cell volume increase with increasing Sm content. The antiferro–ferri–ferromagnetic transition can be observed with increasing Sm content. The samples with x = 0.2 and x = 0.4 order antiferromagnetically at 425 K and 430 K, respectively, and there are the second magnetic phase transitions below 50 K. The sample with x = 0.6, 0.8 and 1.0 become ferri- to ferromagnetically ordered over the whole magnetic ordering temperature range. The corresponding Curie temperatures are 445 K, 450 K and 454 K, respectively. The magnetoresistance (MR) curve of the sample with x = 0.6 in applied magnetic fields of up to 5 T is analysed. The inflexions in the MR–H curves can be interpreted as being due to the influence of the magnetic field on the Fermi surface or due to the competition between the scattering of the magnetic moments and the effect of the Lorentz force on the conduction electrons.