Biquadratic and ring exchange interactions in orthorhombic perovskite manganites
| Autor: | Fedorova, Natalya S., Ederer, Claude, Spaldin, Nicola A., Scaramucci, Andrea |
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| Rok vydání: | 2014 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 91, 165122 (2015) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.91.165122 |
| Popis: | We use ab initio electronic structure calculations within the generalized gradient approximation (GGA+U) to density functional theory (DFT) to determine the microscopic exchange interactions in the series of orthorhombic rare-earth manganites, o-$R$MnO$_3$. Our motivation is to construct a model Hamiltonian (excluding effects due to spin-orbit coupling), which can provide an accurate description of the magnetism in these materials. First, we consider TbMnO$_3$, which exhibits a spiral magnetic order at low temperatures. We map the exchange couplings in this compound onto a Heisenberg Hamiltonian and observe a clear deviation from the Heisenberg-like behavior. We consider first the coupling between magnetic and orbital degrees of freedom as a potential source of non-Heisenberg behavior in TbMnO$_3$, but conclude that it does not explain the observed deviation. We find that higher order magnetic interactions (biquadratic and four-spin ring couplings) should be taken into account for a proper treatment of the magnetism in TbMnO$_3$ as well as in the other representatives of the o-$R$MnO$_3$ series with small radii of the $R$ cation. Comment: 13 pages, 12 figures |
| Databáze: | arXiv |
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