Role of Oxygen Electrons in the Metal-Insulator Transition in the Magnetoresistive Oxide La${}_{2-2x}$Sr${}_{1+2x}$Mn${}_2$O${}_7$ Probed by Compton Scattering

Abstract

We have studied the [100]-[110] anisotropy of the Compton profile in the bilayer manganite. Quantitative agreement is found between theory and experiment with respect to the anisotropy in the two metallic phases (i.e. the low temperature ferromagnetic and the colossal magnetoresistant phase under a magnetic field of 7 T). Robust signatures of the metal-insulator transition are identified in the momentum density for the paramagnetic phase above the Curie temperature. We interpret our results as providing direct evidence for the transition from the metallic-like to the admixed ionic-covalent bonding accompanying the magnetic transition. The number of electrons involved in this phase transition is estimated from the area enclosed by the Compton profile anisotropy differences. Our study demonstrates the sensitivity of the Compton scattering technique for identifying the number and type of electrons involved in the metal-insulator transition.

arXiv comment4 pages, 4 figures, accepted for publication in Physical Review Letters

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• Calculating electron momentum densities and Compton profiles using the linear tetrahedron method
• Renormalization of f-levels away from the Fermi energy in electron excitation spectroscopies: Density functional results of Nd${}_{2-x}$Ce${}_x$CuO${}_4$
• Bulk Fermi surface and momentum density in heavily doped La${}_{2-x}$Sr${}_x$CuO${}_4$ using high resolution Compton scattering and positron annihilation spectroscopies
• Enhancement of Compton Scattering by an Effective Coupling Constant
• A Minimal tight-binding model for ferromagnetic canted bilayer manganites
• The isotropic Compton profile difference across the phase transition of VO${}_2$
• Induced superconductivity in noncuprate layers of the Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$ high-temperature superconductor: Modeling of scanning tunneling spectra
• Probing the semiconductor-to-dirac semimetal transition in Na-Sb-Bi alloys with x-ray Compton scattering