Antiferromagnetic Exchange, Hund's Coupling and the Origin of the Charge Gap in LaMnPO
| Autor: | McNally, D. E., Simonson, J. W., Post, K. W., Yin, Z. P., Pezzoli, M., Smith, G. J., Leyva, V., Marques, C., DeBeer-Schmitt, L., Kolesnikov, A. I., Zhao, Y., Lynn, J. W., Basov, D. N., Kotliar, G., Aronson, M. C. |
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| Rok vydání: | 2014 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | We present inelastic neutron scattering and magnetization measurements of the antiferromagnetic insulator LaMnPO that are well described by a Heisenberg spin model. These measurements are consistent with the presence of two-dimensional magnetic correlations up to a temperature T$_{max}$ $\approx$ 700 K >> T$_{N}$ = 375 K, the N\'eel temperature. Optical transmission measurements show the T = 300 K direct charge gap $\Delta$ = 1 eV has decreased only marginally by 500 K and suggest it decreases by only 10% at T$_{max}$. Density functional theory and dynamical mean field theory calculations reproduce a direct charge gap in paramagnetic LaMnPO only when a strong Hund's coupling J$_{H}$ = 0.9 eV is included, as well as onsite Hubbard U = 8 eV. These results show the direct charge gap in LaMnPO is rather insensitive to antiferromagnetic exchange coupling and instead is a result of the local physics governed by U and J$_{H}$. Comment: 5 pages, 3 figures |
| Databáze: | arXiv |
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