Structural, magnetic and transport properties of Dr_2Fe_(1-x)Cr_xMoO_(6-y)

摘要

The series of Sr_2Fe_(1-x)Cr_xMoO_(6-y) has been synthesized and studied by means of a wide set of experimental techniques. These samples belong to the family of A_2BB'O_6 double perovskites with a ferrimagnetic ground state. The replacement of Fe by Cr leads to samples with a high oxygen deficiency and to increasing cation disorder between B and B' sites. The magnetic moments of these samples decrease as the iron content does. Electrical properties change as well strongly along the series: while Sr_2FeMoO_6 is metallic, the rest of the samples show a semiconducting behavior with an activation energy that increases as the content of Cr does. Only Fe-rich samples exhibit large negative magnetoresistance with the low-field response characteristic of a half-metallic system. The Cr-rich samples display instead a small linear negative magnetoresistance.