Magnetic-Electronic, Conductivity, and Structural Pressure Studies of Sr_2FeO_4 and Sr_3Fe_2O_7
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Sr<SUB>2</SUB>FeO<SUB>4</SUB> and Sr<SUB>3</SUB>Fe<SUB>2</SUB>O<SUB>7</SUB> have been investigated by resistance-temperature, <SUP>57</SUP>Fe-Mössbauer magnetic and x-ray diffraction studies up to ∼30 GPa. Magnetic moments in Sr<SUB>2</SUB>FeO<SUB>4</SUB> remain intact across the conductivity transition to a metallic state at ∼17 GPa. The complex spiral-type magnetic structure at low pressure changes to collinear in the metallic state. In Sr<SUB>3</SUB>Fe<SUB>2</SUB>O<SUB>7</SUB> the original disproportionated state and associated magnetic-electronic structure first exhibits a change at ∼12-15 GPa, and only a single valence state is discernible at P ≥ 21 GPa. A very narrow gapped state prevalent at ∼10 GPa undergoes a sluggish transition to incipient metallic behavior at ∼28 GPa. X-ray data suggest that the magnetic-electronic and conductivity transitions in both compounds are not driven by symmetry-lowering structural transitions.
- The Review of High Pressure Science and Technology
The Review of High Pressure Science and Technology 7, 653-655, 1998
The Japan Society of High Pressure Science and Technology