Magnetism and magnetoresistance of Er 1 x Sm x Mn 6 Ge 6 ( x =0.2–1.0) compounds

Abstract

Magnetic and transport properties of Er1−xSmxMn6Ge6 (x=0.2-1.0) have been investigated by x-ray diffraction (XRD) and magnetization measurement. Analysis of the XRD patterns indicates that the samples with x≤0.4 mainly consist of HfFe6Ge6-type phase and the samples with 0.6≤x≤1.0 mainly consist of YCo6Ge6-type phase (P6/mmm). The lattice constants and the unit cell volume increase with increasing Sm content. The antiferro–ferri–ferromagnetic transitions can be observed with increasing Sm content. The samples with x=0.2 and 0.4 order antiferromagnetically at 420 and 425K, respectively. The samples with x=0.6, 0.8 and 1.0 order from ferri- to ferromagnetically over the whole magnetic ordering temperature range. The corresponding Curie temperatures are 435, 441 and 446K, respectively. The magnetoresistance (MR) isotherms of the sample with x=0.8, measured at various temperatures, are analysed. The magnitude of MR is found to be positive below 55K and gradually increases to a relatively large value of about 5.02% at 5K in a field of 5T as the temperature is lowered. A possible explanation for the positive MR is given.