Defect-induced strong electron-phonon interaction and localization in Sr2FeMo1−xWxO6 „x=0.0, 0.2, 0.5, 0.8, 1.0…

NESTOR E. MASSA; JOSÉ ANTONIO ALONSO; MARÍA JESÚS MARTÍNEZ-LOPE; MARÍA TERESA CASAIS

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

American Institute of Physics

Lugar: Melville; Año: 2005 vol. 72 p. 214303 - 214313

0163-1829

We report on infrared reflectivity and transmission spectra of Sr2FeMoO6 samples with 70% of Fe/Mo cationic ordering. In addition to an overdamped Drude component, localized secondary features are assigned to itinerant carriers interacting strongly with infrared active longitudinal optical modes of quasipolar insulating patches. Their origin is traced to antisite imperfections, and particularly, to antiphase boundary interactions. This implies that carriers are always prone to localization beyond the oxides standard scenario recreating electron localization and small polaron conductivity. Our finding is also supported by a remarkable welldefined second order spectra. The comparison between two samples of Sr2FeMoO6 with 70% and 92% of Fe/Mo cationic ordering shows that by reducing the number the defects, there is an increment in the phonon coherent length yielding a cleaner picture in the most perfectly ordered sample. In Sr2FeMo1-xWxO6 solid solutions that scenario is maintained up to x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 solutions that scenario is maintained up to x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 Fe/Mo cationic ordering shows that by reducing the number the defects, there is an increment in the phonon coherent length yielding a cleaner picture in the most perfectly ordered sample. In Sr2FeMo1-xWxO6 solid solutions that scenario is maintained up to x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 solutions that scenario is maintained up to x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 cationic ordering. In addition to an overdamped Drude component, localized secondary features are assigned to itinerant carriers interacting strongly with infrared active longitudinal optical modes of quasipolar insulating patches. Their origin is traced to antisite imperfections, and particularly, to antiphase boundary interactions. This implies that carriers are always prone to localization beyond the oxides standard scenario recreating electron localization and small polaron conductivity. Our finding is also supported by a remarkable welldefined second order spectra. The comparison between two samples of Sr2FeMoO6 with 70% and 92% of Fe/Mo cationic ordering shows that by reducing the number the defects, there is an increment in the phonon coherent length yielding a cleaner picture in the most perfectly ordered sample. In Sr2FeMo1-xWxO6 solid solutions that scenario is maintained up to x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 solutions that scenario is maintained up to x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 Fe/Mo cationic ordering shows that by reducing the number the defects, there is an increment in the phonon coherent length yielding a cleaner picture in the most perfectly ordered sample. In Sr2FeMo1-xWxO6 solid solutions that scenario is maintained up to x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 solutions that scenario is maintained up to x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 2FeMoO6 samples with 70% of Fe/Mo cationic ordering. In addition to an overdamped Drude component, localized secondary features are assigned to itinerant carriers interacting strongly with infrared active longitudinal optical modes of quasipolar insulating patches. Their origin is traced to antisite imperfections, and particularly, to antiphase boundary interactions. This implies that carriers are always prone to localization beyond the oxides standard scenario recreating electron localization and small polaron conductivity. Our finding is also supported by a remarkable welldefined second order spectra. The comparison between two samples of Sr2FeMoO6 with 70% and 92% of Fe/Mo cationic ordering shows that by reducing the number the defects, there is an increment in the phonon coherent length yielding a cleaner picture in the most perfectly ordered sample. In Sr2FeMo1-xWxO6 solid solutions that scenario is maintained up to x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 solutions that scenario is maintained up to x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 Fe/Mo cationic ordering shows that by reducing the number the defects, there is an increment in the phonon coherent length yielding a cleaner picture in the most perfectly ordered sample. In Sr2FeMo1-xWxO6 solid solutions that scenario is maintained up to x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 solutions that scenario is maintained up to x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 2FeMoO6 with 70% and 92% of Fe/Mo cationic ordering shows that by reducing the number the defects, there is an increment in the phonon coherent length yielding a cleaner picture in the most perfectly ordered sample. In Sr2FeMo1-xWxO6 solid solutions that scenario is maintained up to x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 solutions that scenario is maintained up to x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 2FeMo1-xWxO6 solid solutions that scenario is maintained up to x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 x
0.5 where breathing modes of Fe, Mo, and W octahedra sustain the strongest electron-phonon interaction. The reflectivity of Sr2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1 2FeMo0.2W0.8O6 has well-defined phonon bands, a residual Drude contribution, and a distinctive low temperature small polaron localization. We also found that Sr2FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-12FeWO6 is an insulator structurally stable from 20 to 700 K with a gap about 750 cm-1
95 meV. We conclude that the main clue for understanding low-field magnetoresistance resides in those interacting carriers, their confinement, and the important polaronic effects. interacting carriers, their confinement, and the important polaronic effects. 95 meV. We conclude that the main clue for understanding low-field magnetoresistance resides in those interacting carriers, their confinement, and the important polaronic effects.