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arXiv · 1804.01959

Spin dynamics of the block orbital-selective Mott phase

J. Herbrych·N. Kaushal·A. Nocera·G. Alvarez·A. Moreo·E. Dagotto
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Abstract

Iron-based superconductors display a variety of magnetic phases originating in the competition between electronic, orbital, and spin degrees of freedom. Previous theoretical investigations of the multi-orbital Hubbard model in one dimension revealed the existence of an orbital-selective Mott phase (OSMP) with block spin order. Recent inelastic neutron scattering (INS) experiments on the BaFe$_2$Se$_3$ ladder compound confirmed the relevance of the block-OSMP. Moreover, the powder INS spectrum reveled an unexpected structure, containing both low-energy acoustic and high-energy optical modes. Here we present the theoretical prediction for the dynamical spin structure factor within a block-OSMP regime using the density-matrix renormalization group method. In agreement with experiments we find two dominant features: low-energy dispersive and high-energy dispersionless modes. We argue that the former represents the spin-wave-like dynamics of the block ferromagnetic islands, while the latter is attributed to a novel type of local on-site spin excitations controlled by the Hund coupling.

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J. Herbrych, N. Kaushal, A. Nocera, G. Alvarez, A. Moreo, E. Dagotto. 2018-04-05. Spin dynamics of the block orbital-selective Mott phase. https://doi.org/10.1038/s41467-018-06181-6

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