Magnetic order and properties in heavy fermion (Ce1-XGdX)Ni single crystal

Electronic states of Ni and Ce in the heavy fermion (Ce1-XGdX)Ni system were studied employing magnetic properties. The samples (x = 0.15 and 0.20) showed clear magnetic order, however, the magnetizations in x = 0.15 and 0.20 unexpectedly decreased rapidly with the increase of temperature. The Curie temperatures were clearly determined by the Arrott-plot and the values were 11 K and 17 K, respectively for x = 0.15 and 0.20. The inverse susceptibilities were not linear and showed the characteristic curves for ferri-magnetism. This behaviour suggests that the Ni and/or Ce may be magnetic elements in x = 0.15 and 0.20. Based on the above-mentioned results, molecular-field analysis was carried out within the localized picture and it was found that the Gd-Gd exchange interaction was strongly suppressed and this suppression reflected the rapid decrease of magnetization.