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arXiv · 1010.0129

Orbital Order, Structural Transition and Superconductivity in Iron Pnictides

Yuki Yanagi·Youichi Yamakawa·Naoko Adachi·Yoshiaki Ōno
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Abstract

We investigate the 16-band d-p model for iron pnictide superconductors in the presence of the electron-phonon coupling g with the orthorhombic mode which is crucial for reproducing the recently observed ultrasonic softening. Within the RPA, we obtain the ferro-orbital order below TQ which induces the tetragonal-orthorhombic structural transition at Ts = TQ, together with the stripe-type antiferromagnetic order below TN. Near the phase transitions, the system shows the s++ wave superconductivity due to the orbital fluctuation for a large g case with TQ > TN, while the s+- wave due to the magnetic fluctuation for a small g case with TQ < TN. The former case is consistent with the phase diagram of doped iron pnictides with Ts > TN.

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Yuki Yanagi, Youichi Yamakawa, Naoko Adachi, Yoshiaki Ōno. 2010-12-21. Orbital Order, Structural Transition and Superconductivity in Iron Pnictides. https://doi.org/10.1143/jpsj.79.123707

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