Dynamic susceptibility study of YFexAl12-x (4 <= x <= 5)

Linear and nonlinear susceptibility measurements have been performed in YFexAl12-x (x = 4, 4.7 and 5) intermetallic compounds. This study confirms that long-range order only takes place below the transition temperature values, T-c, previously detected by magnetization and Mossbauer data. Antiferromagnetic interactions are dominant for YFe4Al8. however the enhancement of the magnetic susceptibility with iron content evidences that a ferromagnetic-type ordering with increasing strength develops with the replacement of aluminum by iron atoms. The coexistence of competing antifierromagnetic and ferromagnetic interactions gives rise to magnetic frustration, leading to a complex magnetic behaviour dependent on applied field and temperature. For all compositions, including the ordered YFe4Al8, there is evidence of uncorrelated iron-rich nanoclusters with short-range ferromagnetic-like order above T-c. (C) 2008 Elsevier B.V. All rights reserved.