Itinerant to localized electronic transition in Sr2FeMo1-xWxO6 -: art. no. 064417

Structural, transport, and magnetic measurements on the system Sr2FeMo1-xWxO6 (0 less than or equal tox less than or equal to1) have been used to monitor the transition from itinerant-electron ferromagnetism in Sr2FeMoO6 to localized-electron antiferromagnetism in Sr2FeWO6. An anomalous expansion of the cell volume with increasing x reflects the progressive localization of the minority-spin electrons. The percolation threshold for itinerant pi* electrons occurs in the interval 0.75<x<0.85, and compositions in the range 0.8<x<1.0 exhibit spin-glass behavior. For x less than or equal to0.5, antiferromagnetic coupling across antiphase boundaries produces an M-H hysteresis loop that, although having a low remanence and coercivity, nevertheless saturates by 10 kOe. A peculiar field dependence of the Weiss constant of the paramagnetic molar susceptibility disappears for x greater than or equal to0.25. Transport and structural data are consistent with a relative stabilization of the d(xy) pi* band relative to the d(yzizx) pi* bands at lower temperatures and higher values of x.