Strong Correlation among Structural, Electronic, and Magnetic Properties of Sr2Fe1+xMo1-xO6 (0 ≤ x ≤ 1)

We studied systematic changes of the structural, electric, and magnetic properties in Sr2Fe1+xMo1-xO6 with 0 <= x <= 1, which bridges between a half-metallic double perovskite Sr2FeMoO6 (x = 0) and an antiferromagnetic metal SrFeO3 (= Sr2Fe2O6: x = 1). The lattice volume at room temperature linearly decreases with x. The decline steeply enhances around x = 0.5, which is accompanied with a symmetry change from a tetragonal to a cubic crystal structure. In the same composition, we also found changes in the electronic ground state from a metal to an insulator and in the magnetic one from ferromagnetism to paramagnetism. These results indicate the strong correlation among the crystal structure, itinerant electrons and occurrence of ferromagnetic state in the double perovskite. In addition, the value of the critical composition could reflect peculiar physical changes with x.