We present a detailed structural investigation via neutron diffraction of differently heat treated samples Fe2VAl and Fe2+xV1-xAl. Moreover, the magnetic behaviour of these materials is studied by means of mSR and Mossbauer-experiments. Our structural investigation indicates that quenched Fe2VAl, exhibiting the previously reported "Kondo insulating like" behaviour, is off-stoichiometric (6%) in its Al content. Slowly cooled Fe2VAl is structurally better ordered and stoichiometric, and the microscopic magnetic probes establish long range ferromagnetic order below TC = 13K, consistent with results from bulk experiments. The magnetic state can be modelled as being generated by diluted magnetic ions in a non-magnetic matrix. Quantitatively, the required number of magnetic ions is too large as to be explained by a model of Fe/V site exchange. We discuss the implications of our findings for the ground state properties of Fe2VAl, in particular with respect to the role of crystallographic disorder.
@article{arxiv.cond-mat/0104512,
title = {Structure and magnetic order in Fe2+xV1-xAl},
author = {I. Maksimov and D. Baabe and H. -H. Klauss and F. J. Litterst and R. Feyerherm and D. M. Toebbens and A. Matsushita and S. Suellow},
journal= {arXiv preprint arXiv:cond-mat/0104512},
year = {2009}
}
Comments
accepted for publication in J. Phys.: Condens. Matter