Orbital ordering induces structural phase transition and the resistivity anomaly in iron pnictides

Lv, Weicheng; Wu, Jiansheng; Phillips, Philip

doi:10.1103/physrevb.80.224506

Cited by 271 publications

(271 citation statements)

References 33 publications

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“…6,7 Particularly, it has been shown that the uneven occupation of the d orbitals makes the orthorhombic crystal structure more energetically favorable, thus inducing a structural phase transition at T s . 2,8 However, the large electronic anisotropy revealed in Ba(Fe 1−x Co x ) 2 As 2 precisely where the crystal's C 4 rotational symmetry is broken can not be explained based on the 1% lattice distortion at T s . 9 In fact, it has been shown the presence of a C 4 structural to C 2 electronic symmetry transition in the quasi-particle interference maps of Ca(Fe 1−x Co x ) 2 As 2 .…”

Section: A Introductionmentioning

confidence: 99%

Filamentary superconductivity across the phase diagram of Ba(Fe,Co)2As2

Xiao

et al. 2012

Phys. Rev. B

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We show magnetotransport results on Ba(Fe1−xCox)2As2 (0.0 ≤ x ≤ 0.13) single crystals. We identify the low temperature resistance step at 23 K in the parent compound with the onset of filamentary superconductivity (FLSC), which is suppressed by an applied magnetic field in a similar manner to the suppression of bulk superconductivity (SC) in doped samples. FLSC is found to persist across the phase diagram until the long range antiferromagnetic order is completely suppressed. A significant suppression of FLSC occurs for 0.02 < x < 0.04, the doping concentration where bulk SC emerges. Based on these results and the recent report of an electronic anisotropy maximum for 0.02 ≤ x ≤ 0.04 [Science 329, 824 (2010)], we speculate that, besides spin fluctuations, orbital fluctuations may also play an important role in the emergence of SC in iron-based superconductors.

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Section: A Introductionmentioning

confidence: 99%

Filamentary superconductivity across the phase diagram of Ba(Fe,Co)2As2

Xiao

et al. 2012

Phys. Rev. B

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“…20 In the orbital nematicity scenario the difference in populations n Xz − n Y z of the d Xz and d Y z iron orbitals is believed to be the primary cause of the nematic transition. [21][22][23][24][25] In another scenario it is the spin that drives the nematic transition. 20,26 Let m 1,2 be the two staggered (antiferromagnetic) magnetizations on the even and odd iron sublattices, respectively.…”

Section: Introductionmentioning

confidence: 99%

Raman scattering as a probe of nematic correlations

Khodas

Levchenko

2015

Phys. Rev. B

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We use the symmetry-constrained low-energy effective Hamiltonian of iron-based superconductors to study the Raman scattering in the normal state of underdoped iron-based superconductors. The incoming and scattered Raman photons couple directly to orbital fluctuations and indirectly to the spin fluctuations. We computed both couplings within the same low-energy model. The symmetry-constrained Hamiltonian yields the coupling between the orbital and spin fluctuations of only the same symmetry type. Attraction in the B2g symmetry channel was assumed for the system to develop the subleading instability towards the discrete in-plane rotational symmetry breaking, referred to as Ising nematic transition. We find that upon approaching this instability, the Raman spectral function develops a quasielastic peak as a function of energy transferred by photons to the crystal. We attribute this low-energy B2g scattering to the critical slowdown associated with the build up of nematic correlations.

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“…In the first, the structural order is unrelated to magnetism and is driven by orbital ordering as the primary instability. The orbital ordering induces magnetic anisotropy and triggers the magnetic transition at a lower temperature by renormalizing the exchange constants [16][17][18] . This scenario is largely phenomenological, but there have been recent efforts to develop a microscopic basis 19 .…”

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confidence: 99%

Magnetically driven suppression of nematic order in an iron-based superconductor

et al. 2014

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A theory of superconductivity in the iron-based materials requires an understanding of the phase diagram of the normal state. In these compounds, superconductivity emerges when stripe spin density wave (SDW) order is suppressed by doping, pressure or atomic disorder. This magnetic order is often pre-empted by nematic order, whose origin is yet to be resolved. One scenario is that nematic order is driven by orbital ordering of the iron 3d electrons that triggers stripe SDW order. Another is that magnetic interactions produce a spin-nematic phase, which then induces orbital order. Here we report the observation by neutron powder diffraction of an additional fourfold-symmetric phase in Ba 1 À x Na x Fe 2 As 2 close to the suppression of SDW order, which is consistent with the predictions of magnetically driven models of nematic order.

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Orbital ordering induces structural phase transition and the resistivity anomaly in iron pnictides

Cited by 271 publications

References 33 publications

Filamentary superconductivity across the phase diagram of Ba(Fe,Co)2As2

Filamentary superconductivity across the phase diagram of Ba(Fe,Co)2As2

Raman scattering as a probe of nematic correlations

Magnetically driven suppression of nematic order in an iron-based superconductor

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