Antiferromagnetic-to-ferromagnetic transition induced by aluminum in the Ti(Fe1−xAlx)2 intermetallic compounds: a 57Fe Mössbauer spectroscopy study

Mossbauer spectroscopy has been used to investigate the hyperfine field distributions and the local spin configurations of Fe atoms in the magnetically ordered Ti(Fe1−xAlx)2 compounds. The evolution of the spin arrangement of the Fe atoms was observed over the concentration range 0 ≤ x ≤ 0.25 at 5 K. The Al impurity suppresses the ferromagnetic exchange in the Fe(6h) layers and simultaneously provides the conditions for a transition of the Fe(2a) atoms, which are nonmagnetic in the TiFe2 compound, to the states with nonzero magnetic moment. The magnetic behavior of the Fe(2a) atoms is the key factor governing the anti- to ferromagnetic transition in the Ti(Fe1−xAlx)2 compounds. The magnetic ordering temperatures of the Ti(Fe1−xAlx)2 compounds were determined. In addition, the parameters of the electric-field gradient in TiFe2 as well as the relationship between the value of the magnetic moment of the Fe atom and the type of atomic configuration were discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)