La-induced changes in the magnetic and electronic properties ofSr2−xLaxFeMoO6

Abstract

We report the results from a study of lanthanum doping in the Sr 2 FeMoO 6 half-metallic double perovskites. The thermoelectric power systematically increases with electron doping, and the temperature dependence is remarkably similar to that reported in the superconducting cuprates. This suggests a common mechanism and we interpret the data in terms of a model applied to the superconducting cuprates. There is a systematic decrease in the saturation magnetization with La doping, which is predominately due to an increase in the Fe-Mo antisite disorder. Even though there is a large decrease in the saturation magnetization, surprisingly we find that the low-temperature magnetization can be described within the three-dimensional Heisenberg model. The saturation magnetization is shown to extrapolate to zero for ϳ44% antisite disorder, which is close to the maximum of 50% ͑i.e., completely random Mo-Fe site occupancy͒.

Effect of the itinerant electron density on the magnetization and Curie temperature of Sr2FeMoO6 ceramics

“…As discussed in the introduction, a considerable high T C of SFMO origins from the strong magnetic interactions via a double-exchange-like mechanism. Ferromagnetic coupling strengthen is proposed to be mediated by n. Actually, T C indeed can be signicantly improved by electron doped FeMo-based double perovskites, 16,[18][19][20][21][22]45,46 and it is noted that the theoretical n of such subjects investigated are greater than 1. And T C values have a monotonously positive correlation with n due to the electron band lling effect.…”

“…For improved T C can be observed due to the increased electron density caused by electron injection into the conduction band. 9,16,[18][19][20][21][22][23][24] Contrary to the T C response, the Fe/Mo ordering degree, saturated magnetization and magnetoresistance are reduced. 9,18,21,25,26 However, reports of the effect of hole-doping on the carrier density and the physical properties are relatively rare.…”

“…The efficient optimized T C strategies have been also proposed in the electron doped FeMo-based perovskites. 16,18,21,46 …”

“…11,13,14 The itinerant electron contributed by the Mo 5+ cation mediates the ferromagnetic coupling between neighbour Fe cations via a double-exchangelike model. 3,[15][16][17] The strengthen of the ferromagnetic interaction has a direct correlation with the density of the electron at the conduction band, which can be modied effectively by electron-doping or hole-doping. For improved T C can be observed due to the increased electron density caused by electron injection into the conduction band.…”

Characterization of magnetic property of double-perovskite (Sr2−xGdx)FeMoO6

“…In the past few years, many studies have been carried out on tuning and optimizing the magnetic properties of Sr 2 FeMoO 6 double perovskite by doping at Sr sub-lattice with trivalent rare earth ions [3,[14][15][16][17][18]. The magnetic properties of La-, Ce-, Pr-, Nd-, Smand Eu-doped Sr 2 FeMoO 6 had been investigated in our previous work as well [19,20].…”