Emergence of orbital nematicity in the tetragonal phase of BaFe2(As1-xPx)2

Tetsuya Iye, Marc Henri Julien, Hadrien Mayaffre, Mladen Horvatić, Claude Berthier, Kenji Ishida, Hiroaki Ikeda, Shigeru Kasahara, Takasada Shibauchi, Yuji Matsuda

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40 Citations (Scopus)

Abstract

We report on 75As-NMR measurements in single crystalline BaFe2(As0.96P0.04)2 for magnetic fields parallel to the orthorhombic [110]o and [100]o directions above the structural transition temperature TS ≃ 121 K. A large difference in the linewidth between the two field directions reveals in-plane anisotropy of the electric field gradient, even in the tetragonal phase. This provides microscopic evidence of population imbalance between As-4px and 4py orbitals, which reaches |nx - ny| /|nx + ny| ∼ 15% at T → TS and is a natural consequence of the orbital ordering of Fe-3dxz and dyz electrons. Surprisingly, this orbital polarization is found to be already static near room temperature, suggesting that it arises from the pinning of anisotropic orbital fluctuations by disorder. The effect is found to be stronger below ∼160 K, which coincides with the appearance of nematicity in previous torque and photoemission measurements. These results impose strong constraints on microscopic models of the nematic state.

Original languageEnglish
Article number043705
Journaljournal of the physical society of japan
Volume84
Issue number4
DOIs
Publication statusPublished - Apr 15 2015
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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