Double stage nematic bond-ordering above double stripe magnetism: application to BaTi$_2$Sb$_2$O
| Autor: | Zhang, G., Glasbrenner, J. K., Flint, R., Mazin, I. I., Fernandes, R. M. |
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| Rok vydání: | 2016 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 95, 174402 (2017) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.95.174402 |
| Popis: | Spin-driven nematicity, or the breaking of the point-group symmetry of the lattice without long-range magnetic order, is clearly quite important in iron-based superconductors. From a symmetry point of view, nematic order can be described as a coherent locking of spin fluctuations in two interpenetrating N\'eel sublattices with ensuing nearest-neighbor bond order and an absence of static magnetism. Here, we argue that the low-temperature state of the recently discovered superconductor BaTi$_2$Sb$_2$O is a strong candidate for a more exotic form of spin-driven nematic order, in which fluctuations occurring in four N\'eel sublattices promote both nearest- and next-nearest neighbor bond order. We develop a low-energy field theory of this state and show that it can have, as a function of temperature, up to two separate bond-order phase transitions -- namely, one that breaks rotation symmetry and one that breaks reflection and translation symmetries of the lattice. The resulting state has an orthorhombic lattice distortion, an intra-unit-cell charge density wave, and no long-range magnetic order, all consistent with reported measurements of the low-temperature phase of BaTi$_2$Sb$_2$O. We then use density functional theory calculations to extract exchange parameters to confirm that the model is applicable to BaTi$_2$Sb$_2$O. Comment: 18 pages, 10 figures |
| Databáze: | arXiv |
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