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Jensen, Maria Fuglsang; Brouet, V.; Papalazarou, E.; Nicolaou, A.; Taleb‐Ibrahimi, A.; Fèvre, P. Le; Bertran, F.; Forget, A.; Colson, D.

doi:10.1103/physrevb.84.014509

Cited by 31 publications

(26 citation statements)

References 38 publications

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“…In the ( , 0 π ) state with exchange field parameters same as used in figure 7(a), electron fillings in different orbitals are obtained as n xz ≈ 1.2, n yz ≈ 1.0 and n xy ≈ 0.8. This sign of ferro-orbital order (n n xz yz > ) is in agreement with experiments [10,[13][14][15]. As highlighted earlier [50], the presence of hopping anisotropy ( t t 1 2 | | < | |) along with anisotropic ( , 0 π ) magnetic order breaks the equivalence between a and b directions, and naturally leads to orbital ordered state.…”

Section: Orbital Orderingsupporting

confidence: 89%

“…The FS goes through a complex multi-orbital reconstruction through the paramagnetic-to-AF transition [8,10]. Apart from the FS structure, ARPES [10,13,14] and XLD [15] experiments have also revealed the existence of ferro orbital order between d xz and d yz Fe orbitals. In the magnetic state, the Fe d yz band is shifted up relative to the d xz band, causing electron density difference between the two orbitals, which may cause structural phase transition [16].…”

Section: Introductionmentioning

confidence: 99%

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Electronic structure, spin excitations, and orbital ordering in a three-orbital model for iron pnictides

Ghosh

Singh

2015

New J. Phys.

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A three-orbital itinerant-electron model involving d xz , d yz and d xy Fe 3d orbitals is proposed for iron pnictides towards understanding the ( , 0 π ) ordered magnetism and magnetic excitations in these materials. It is shown that this model at half filling yields a gapped ( , 0 π ) magnetic state, and simultaneously reproduces several experimentally observed features such as the electronic structure, spin excitations, as well as the ferro orbital order between the d xz and d yz orbitals.interaction strength U c for ( , 0 π ) ordering. However, spin wave dispersion in this model does not agree in detail with INS measurements [27,28]. Moreover, it does not include d xy Fe orbital which contributes some portions of the electron pockets. Similarly, three-orbital models with one-third filling (i.e. two electrons in three orbitals) [29], two-third filling (i.e. four electrons in three orbitals) [30,31], and four-orbital model at half-filling [32] can reproduce the desired FS structure, but spin wave excitations in these models have not been investigated yet. More realistic five-orbital models [33][34][35], which yield the FS topology similar to experimental findings, were proposed aimed at investigation of pairing instabilities, but spin excitations were not studied. Although anisotropic spin wave excitation was obtained in a recent study [36] for a five-orbital model [37], investigation of spin excitations over the entire BZ was not carried out.In this context, we present and investigate a three-orbital itinerant-electron model in this paper. We find that this minimal model simultaneously yields the correct FS structure as well as spin wave dispersion consistent with INS experiments. Moreover, ferro orbital order of appropriate sign is also obtained in this model.The organization of this paper is as follows. The importance of ferromagnetic (F) spin couplings on the experimentally measured spin wave dispersion in the ( , 0 π ) state is briefly discussed in section 2. Then in section 3, it is shown that no F spin coupling is generated in the two-band model with FS nesting [24] ,although this model yields correct FS topology. A third d xy Fe orbital is therefore necessary to overcome this shortcoming, and a three-orbital model having d xz , d yz and d xy Fe 3d orbitals is presented in section 4 highlighting the FS and DOS. The investigation of magnetic excitations and orbital ordering in the ( , 0 π ) magnetic state is carried out in section 5. Finally conclusions are discussed in section 6. Spin wave energy at the ferromagnetic zone boundary and ferromagnetic spin couplingIn order to highlight the effect of induced F spin couplings on the spin wave dispersion and spin wave energy at the FZB, we consider the case of single band Hubbard model with nearest-neighbor (NN) hopping t and nextnearest-neighbor (NNN) hopping t′. In this case, the spin wave dispersion in the strong coupling limit [38] is given by ( ) J J J b q J J q q H U n n U J n n J J a a a a S S

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Section: Orbital Orderingsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Electronic structure, spin excitations, and orbital ordering in a three-orbital model for iron pnictides

Ghosh

Singh

2015

New J. Phys.

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“…This compound corresponds to optimal Co doping for superconductivity (T c = 23 K), but we have obtained similar spectra for BaFe 2 As 2 (Ref. 15) and other Co dopings. A complexity of ARPES in iron pnictides is that there are 2 Fe per unit cell, which doubles the number of bands.…”

Section: Introductionsupporting

confidence: 71%

“…In Ref. 15, we correctly assigned it to d xy , because of its dispersion, but we did not understand its parity.…”

Section: A Assignment Of the Different Bandsmentioning

confidence: 99%

Impact of the two Fe unit cell on the electronic structure measured by ARPES in iron pnictides

et al. 2012

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In all iron pnictides, the positions of the ligand alternatively above and below the Fe plane create 2 inequivalent Fe sites. This results in 10 Fe 3d bands in the electronic structure. However, they do not all have the same status for an ARPES experiment. There are interference effects between the 2 Fe that modulate strongly the intensity of the bands and that can even switch their parity. We give a simple description of these effects, notably showing that ARPES polarization selection rules in these systems can not be applied by reference to a single Fe ion. We show that ARPES data for the electron pockets in Ba(Fe 0.92 Co 0.08 ) 2 As 2 are in excellent agreement with this model as well as with direct calculation of the spectral weight. We observe both the total suppression of some bands and the parity switching of some other bands. Once these effects are properly taken into account, the structure of the electron pockets, as measured by ARPES, becomes very clear and simple. By combining ARPES measurements in different experimental configurations, we clearly isolate each band forming one of the electron pockets. We identify a deep electron band along one ellipse axis with the d xy orbital and a shallow electron band along the perpendicular axis with the d xz /d yz orbitals, in good agreement with band-structure calculations. We show that the electron pockets are warped as a function of k z as expected theoretically, but that they are much smaller than predicted by the calculation.

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“…A normal state feature around 0.1 eV also appears in the conductivity spectra calculated by Yin, Haule, and Kotliar. 38 The three bands are discernible in angle-resolved photoemission spectroscopy spectra, [39][40][41][42][43] for example, in Fig. 1 Fig.…”

mentioning

confidence: 96%

Low-energy interband transitions in the infrared response of Ba(Fe1−xCox
Maršík
¹
,
Wang
²
,
Rössle
³

et al. 2013
Phys. Rev. B
31
8
46
0
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We studied the doping and temperature (T ) dependence of the infrared (IR) response of Ba(Fe 1-x Co x ) 2 As 2 single crystals. We show that a weak band around 1000 cm −1 , that was previously interpreted in terms of interaction of the charge carriers with magnetic excitations or of a pseudogap, is rather related to low-energy interband transitions. Specifically, we show that this band exhibits a similar doping and T dependence as the hole pockets seen by angle resolved photoemission spectroscopy (ARPES). Notably, we find that it vanishes as a function of doping near the critical point where superconductivity is suppressed in the overdoped regime. Our IR data thus provide bulk specific information (complementary to the surface sensitive ARPES) for a Lifshitz transition. Our IR data also reveal a second low-energy band around 2300 cm −1 which further emphasizes the necessity to consider the multiband nature of these iron arsenides in the analysis of the optical response.

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Angle-resolved photoemission study of the role of nesting and orbital orderings in the antiferromagnetic phase of BaFe2As2

Cited by 31 publications

References 38 publications

Electronic structure, spin excitations, and orbital ordering in a three-orbital model for iron pnictides

Electronic structure, spin excitations, and orbital ordering in a three-orbital model for iron pnictides

Impact of the two Fe unit cell on the electronic structure measured by ARPES in iron pnictides

Low-energy interband transitions in the infrared response of Ba(Fe1−xCox
Maršík
¹
,
Wang
²
,
Rössle
³

et al. 2013
Phys. Rev. B
31
8
46
0
View full text Add to dashboard Cite

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Angle-resolved photoemission study of the role of nesting and orbital orderings in the antiferromagnetic phase of BaFe2As2

Cited by 31 publications

References 38 publications

Electronic structure, spin excitations, and orbital ordering in a three-orbital model for iron pnictides

Electronic structure, spin excitations, and orbital ordering in a three-orbital model for iron pnictides

Impact of the two Fe unit cell on the electronic structure measured by ARPES in iron pnictides

Low-energy interband transitions in the infrared response of Ba(Fe1−xCoxMaršík1, Wang2, Rössle3 et al. 2013Phys. Rev. B318460View full textAdd to dashboardCite

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Low-energy interband transitions in the infrared response of Ba(Fe1−xCox
Maršík
¹
,
Wang
²
,
Rössle
³

et al. 2013
Phys. Rev. B
31
8
46
0
View full text Add to dashboard Cite