Electron doping effects on Sr2FeReO6

We substitute La for Sr in the Sr2FeReO6 double perovskite to see how electron doping affects its properties. Sr2−xLaxFeReO6 compounds can be prepared up to x = 0.5. Beyond this value, a secondary phase is formed. The replacement of Sr by La leads to an increase of the unit cell volume and to a rise of the Curie temperature. However, both the saturated magnetic moment and the room-temperature magnetoresistance decrease with increasing the La content. The substituted compounds are magnetically hard and show maxima in the electrical resistivity at field values close to the coercive field. Our structural study reveals a low content of anti-site defects for all samples studied. The average Fe–O bond lengths remain almost constant upon doping whereas the Re–O distances increase as x increases. This suggests that electrons mainly go to the Re orbitals.

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