Anisotropic quasiparticle lifetimes in Fe-based superconductors

Kemper, A. F.; Korshunov, M. M.; Devereaux, T. P.; Fry, J. N.; Cheng, Hai‐Ping; Hirschfeld, P. J.

doi:10.1103/physrevb.83.184516

Cited by 45 publications

(54 citation statements)

References 48 publications

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“…We find that, both for hole and electron pockets, the lifetimes are about twice longer on the d xy parts of the FS than on the d xz /d yz parts. These anisotropies are in good agreement with a recent study by Kemper et al [16]. As the d xy parts of the electron pockets are also associated with higher Fermi velocities on the electron pockets, this probably explains why electrons dominate in many experimental techniques.…”

supporting

confidence: 92%

“…One could imagine a situation where local moments would form preferentially in this band, while d xy would be principally responsible for the metallicity. Recently, Kemper et al predicted a strong anisotropy of the lifetimes between d xy and d xz /d yz [16], which appears qualitatively very similar to this finding. However, this anisotropy depends sensitively on the nesting between the different bands and, as their model did not include a d xy hole band, it cannot be directly compared.…”

supporting

confidence: 72%

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Opening of the superconducting gap in the hole pockets of Ba(Fe1−xCox)2
Mansart
¹
,
Papalazarou
²
,
Brouet
³

et al. 2012
Phys. Rev. B
5
0
4
0
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Despite many ARPES investigations of iron pnictides, the structure of the electron pockets is still poorly understood. By combining ARPES measurements in different experimental configurations, we clearly resolve their elliptic shape. Comparison with band calculation identify a deep electron band with the dxy orbital and a shallow electron band along the perpendicular ellipse axis with the dxz/dyz orbitals. We find that, for both electron and hole bands, the lifetimes associated with dxy are longer than for dxz/dyz. This suggests that the two types of orbitals play different roles in the electronic properties and that their relative weight is a key parameter to determine the ground state.PACS numbers: 79.60.-i, 71.18.-y, 71.30.-h There is a consensus that the multiband nature of iron pnictides is essential for defining their electronic properties. Many models for the superconducting and antiferromagnetic orders heavily rely on the interaction between different electron and hole Fermi Surface (FS) sheets [1,2]. On the experimental side, transport [3,4], Raman [5,6] and quantum oscillations experiments [7,8] seem to detect predominantly electrons, suggesting they have longer lifetimes than holes. However, ARPES experiments that can image independently hole and electron bands has not evidenced so far a clear difference between them that could explain this behavior. In fact, it has been more difficult to clearly image the electron pockets than the hole pockets with ARPES [9][10][11]. Recently, an ARPES study resolved them in more details [12], but proposed a structure so different from theory, that it clearly calls for more investigation.In this paper, we report ARPES measurements in Ba(Fe 0.92 Co 0.08 ) 2 As 2 , which corresponds to optimal Co doping for superconductivity (T c =23K). Similar features are found for other members of the BaFe 2 As 2 family [13]. We first clarify that, in appropriate experimental conditions, only the electron pockets of the 1Fe-Brillouin Zone (BZ) [14] are observed, which greatly simplifies the spectra. The electron pocket is an ellipse made out of two different orbitals with opposite parities and markedly different dispersions. Along one axis, the band is odd and very shallow (50meV), while it is even and much deeper (more than 100meV) along the perpendicular axis. These dispersions correspond very well to band structures renormalized by a factor of 3, suggesting to associate the shallow band with the d xz /d yz orbitals and the deep band with the d xy orbital. The parity measured by ARPES for the deep electron band is not that expected for d xy , which is due to interferences between the 2 Fe of the unit cell [15]. We find that, both for hole and electron pockets, the lifetimes are about twice longer on the d xy parts of the FS than on the d xz /d yz parts. These anisotropies are in good agreement with a recent study by Kemper et al. [16]. As the d xy parts of the electron pockets are also associated with higher Fermi velocities on the electron pockets, this probably explains why ...

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supporting

confidence: 92%

supporting

confidence: 72%

Opening of the superconducting gap in the hole pockets of Ba(Fe1−xCox)2
Mansart
¹
,
Papalazarou
²
,
Brouet
³

et al. 2012
Phys. Rev. B
5
0
4
0
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“…30,31 In addition, the multi-orbital structure of each Fermi pocket also affects the anisotropy of the scattering rate. As shown in Fig.…”

Section: -10mentioning

confidence: 99%

Evolution of transport properties of BaFe2−xRuxAs2i

Eom

Hoch

et al. 2012

Phys. Rev. B

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The effects of isovalent Ru substitution at the Fe sites of BaFe2−xRuxAs2 are investigated by measuring resistivity (ρ) and Hall coefficient(RH ) on high-quality single crystals in a wide range of doping (0 ≤ x ≤ 1.4). Ru substitution weakens the antiferromagnetic (AFM) order, inducing superconductivity for relatively high doping level of 0.4 ≤ x ≤ 0.9. Near the AFM phase boundary, the transport properties show non-Fermi-liquid-like behavior with a linear-temperature dependence of ρ and a strong temperature dependence of RH with a sign change. Upon higher doping, however, both ρ and RH recover conventional Fermi-liquid behavior. Strong doping dependence of RH together with a small magnetoresistance suggest that the anomalous transport properties can be explained in terms of anisotropic charge carrier scattering due to interband AFM fluctuations rather than a conventional multi-band scenario.PACS numbers: 74.70. Xa, 74.25.Dw, 74.40.Kb Unconventional superconductivity in the proximity of an antiferromagnetic (AFM) phase has been intensively studied on high-T c cuprates, heavy-fermion superconductors and the recently-discovered Fe-pnictides.1 In spite of subtle differences in their detailed properties, there is a growing body of evidence that they all exhibit a common phase diagram where inside a dome-shaped regime a superconducting phase appears as the AFM phase is suppressed by an external control parameter, such as doping or pressure. Even though the static AFM order is fully suppressed, AFM fluctuations survive and they can strongly modify the quasi-particle scattering spectrum, leading e. g. to the so-called non-Fermi-liquid-like transport properties. Clarifying the nature of the nonfermi-liquid behavior and understanding its relation to superconductivity are key issues for elucidating the unconventional superconductivity in Fe-pnitides.In Fe-pnictides, the AFM instability is closely related to the interband nesting between electron-and holeFermi surfaces (FS's).2-4 Degrading the nesting condition by introducing additional charge carriers or modifying the crystal structure suppress the AFM order and eventually induce superconductivity. So far, various types of chemical substitution have been employed in order to explore the phase diagram of Fe pnictides. In the so-called 122 pnictides, the substitution dependence of the electrical transport properties has been intensively studied e.g. for BaFe 2 As 2 with K-5 , Co-6-9 and P-substitution 10 at the Ba, Fe and As sites, respectively. Deviations from a T 2 -power-law dependence of the electrical resistivity (ρ) or the enhancement of the Hall coefficient (R H ) at low temperatures 8,10 have been commonly observed in various Fe-pnictides. These observations are usually considered as experimental indication for non-Fermi-liquid behavior. In Fe-pnictides, however, such deviations have also been ascribed to multi-band transport 8,9 , where a conventional description of different types of carriers is sufficient.In this respect, it is interesting to investigate how th...

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“…In such a case, the simple multicarrier models used above do not hold quantitatively [57,58]: estimated carrier densities may deviate from actual ones. An intuitive explanation for this would be that parts of the FS where scattering is particularly strong, dubbed hot spots, contribute little to the electrical transport and hence they are missed, although a recent theory suggests a more involved explanation [58].…”

Section: Fig 2 (Color Online)mentioning

confidence: 99%

Magnetotransport study of the pressure-induced antiferromagnetic phase in FeSe

Terashima¹,

Kikugawa²,

Kasahara³

et al. 2016

Phys. Rev. B

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The resistivity ρ and Hall resistivity ρH are measured on FeSe at pressures up to P = 28.3 kbar in magnetic fields up to B = 14.5 T. The ρ(B) and ρH (B) curves are analyzed with multicarrier models to estimate the carrier density and mobility as a function of P and temperature (T 110 K). It is shown that the pressure-induced antiferromagnetic transition is accompanied by an abrupt reduction of the carrier density and scattering. This indicates that the electronic structure is reconstructed significantly by the antiferromagnetic order.PACS numbers: 74.70. Xa, 72.15.Gd, 74.25.Dw, 74.25.Jb Since the discovery of superconductivity (SC) at T c = 26 K in LaFeAs(O 1−x F x ) by Kamihara et al.[1], the iron-based high-T c materials have intensively been studied. Yet, the paring mechanism is still highly controversial: some propose spin fluctuations as the glue [2, 3], while others orbital ones [4, 5]. Intimately related to this issue is the origin of the nematic transition [6]. Typical iron-pnictide parent compounds such as LaFeAsO or BaFe 2 As 2 [7,8] exhibit a tetragonal-toorthorhombic structural transition at T s , slightly above or at the same temperature as a stripe-type antiferromagnetic (AFM) order at T N . Electronic properties below T s exhibit in-plane anisotropy that is much stronger than expected from the slight orthorhombic distortion [9][10][11][12]. It is therefore believed that the structural transition is driven by electronic (i.e., spin or orbital) degrees of freedom and thus it is called a nematic transition. T s and T N are reduced simultaneously by pressure or chemical substitution, resulting in a phase diagram where the AFM phase is enclosed by the nematic one [9]. This is consistent with scenarios of spin-driven nematicity [6,13]. An SC dome appears around points where T s and T N reach zero.) initially attracted attention because of a remarkable enhancement of T c by pressure [15][16][17][18]. A report of T c > 50 K in single-layer films [19] has also aroused considerable interest. At the same time, FeSe may be crucial in determining the paring glue and the origin of the nematicity in the iron-based superconductors. It undergoes a structural transition at T s ∼ 90 K but does not order magnetically at ambient pressure [20]. A large splitting of the d xz and d yz bands below ∼ T s found by angle-resolved photoemission spectroscopy indicates that the transition at T s is a nematic one accompanied by orbital polarization [21][22][23]. An AFM transition can be induced by pressure [24][25][26]. However, the phase diagram (see Fig. 1 and [26][27][28]) is distinct from the typical one described above for the iron-pnictide compounds. This casts some doubts on the spin-nematic scenarios. It is however to be noted that low-energy AFM spin fluctuations have been observed below T s in NMR and inelastic neutron scattering measurements [29][30][31][32][33][34]. In addition, very recent reports suggest that at high pressures (P 18 kbar, Fig. 1) where no separate structural transition at T s is seen the AFM tr...

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Anisotropic quasiparticle lifetimes in Fe-based superconductors

Cited by 45 publications

References 48 publications

Opening of the superconducting gap in the hole pockets of Ba(Fe1−xCox)2
Mansart
¹
,
Papalazarou
²
,
Brouet
³

et al. 2012
Phys. Rev. B
5
0
4
0
View full text Add to dashboard Cite

Opening of the superconducting gap in the hole pockets of Ba(Fe1−xCox)2
Mansart
¹
,
Papalazarou
²
,
Brouet
³

et al. 2012
Phys. Rev. B
5
0
4
0
View full text Add to dashboard Cite

Evolution of transport properties of BaFe2−xRuxAs2i

Magnetotransport study of the pressure-induced antiferromagnetic phase in FeSe

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Anisotropic quasiparticle lifetimes in Fe-based superconductors

Cited by 45 publications

References 48 publications

Opening of the superconducting gap in the hole pockets of Ba(Fe1−xCox)2Mansart1, Papalazarou2, Brouet3 et al. 2012Phys. Rev. B5040View full textAdd to dashboardCite

Opening of the superconducting gap in the hole pockets of Ba(Fe1−xCox)2Mansart1, Papalazarou2, Brouet3 et al. 2012Phys. Rev. B5040View full textAdd to dashboardCite

Evolution of transport properties of BaFe2−xRuxAs2i

Magnetotransport study of the pressure-induced antiferromagnetic phase in FeSe

Contact Info

Product

Resources

About

Opening of the superconducting gap in the hole pockets of Ba(Fe1−xCox)2
Mansart
¹
,
Papalazarou
²
,
Brouet
³

et al. 2012
Phys. Rev. B
5
0
4
0
View full text Add to dashboard Cite

Opening of the superconducting gap in the hole pockets of Ba(Fe1−xCox)2
Mansart
¹
,
Papalazarou
²
,
Brouet
³

et al. 2012
Phys. Rev. B
5
0
4
0
View full text Add to dashboard Cite