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arXiv · 0905.1704

Orbital-Ordering Induces Structural Phase Transition and the Resistivity Anomaly in Iron Pnictides

Weicheng Lv·Jiansheng Wu·Philip Phillips
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Abstract

We attribute the structural phase transition (SPT) in the parent compounds of the iron pnictides to orbital ordering. Due to the anisotropy of the $d_{xz}$ and $d_{yz}$ orbitals in the $xy$ plane, a ferro-orbital ordering makes the orthorhombic structure more energetically favorable, thus inducing the SPT. In this orbital-ordered system, the sites with orbitals that do not order have higher energies. Scattering of the itinerant electrons by these localized two-level systems causes a resistivity anomaly upon the onset of the SPT. The proposed orbital ordering also leads to the stripe-like anti-ferromagnetism and anisotropy of the magnetic exchanges. This model is quantitatively consistent with available experimental observations.

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Weicheng Lv, Jiansheng Wu, Philip Phillips. 2009-12-12. Orbital-Ordering Induces Structural Phase Transition and the Resistivity Anomaly in Iron Pnictides. https://doi.org/10.1103/physrevb.80.224506

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