Fermi Surface of Three-Dimensional La(1-x)Sr(x)MnO3 Explored by Soft-X-Ray ARPES: Rhombohedral Lattice Distortion and its Effect on Magnetoresistance.

Electronic structure of the three-dimensional colossal magnetoresistive perovskite La1−xSrxMnO3 has been established using soft-x-ray angle-resolved photoemission spectroscopy with its intrinsically sharp definition of three-dimensional electron momentum. The experimental results show much weaker polaronic coupling compared to the bilayer manganites and are consistent with the theoretical band structure including the empirical Hubbard parameter U. The experimental Fermi surface unveils the canonical topology of alternating three-dimensional electron spheres and hole cubes, with their shadow contours manifesting the rhombohedral lattice distortion. This picture has been confirmed by one-step photoemission calculations including displacement of the apical oxygen atoms. The rhombohedral distortion is neutral to the Jahn-Teller effect and thus polaronic coupling, but affects the double-exchange electron hopping and thus the colossal magnetoresistance effect. DOI: 10.1103/PhysRevLett.114.237601 PACS numbers: 79.60.-i, 71.18.+y, 75.47.Gk, 75.47.Lx Hole-doped manganites with the general chemical formula ðLa; SrÞ x MnOy (LSMO) are typical transition metal oxides (TMOs) with perovskite structure, which have attracted tremendous interest due to the discovery of their colossal magnetoresistance (CMR). Coupling of charge, orbital, spin, and lattice degrees of freedoms results in a rich phase diagram of these materials, extending over antiferromagnetic, ferromagnetic (FM), and paramagnetic (PM) insulating and metallic states. The electron transport in manganites is coupled to their ferromagnetism and is generally described in the framework of the double-exchange (DE) mechanism. However, an important role in physics of these materials can be played by polaronic effects coupling of the electron and lattice