Fine structure of the incommensurate antiferromagnetic fluctuations in single-crystalline LiFeAs studied by inelastic neutron scattering

Qureshi, N.; Steffens, P.; Lamago, D.; Sidis, Y.; Sobolev, Oleg; Ewings, R. A.; Harnagea, Luminita; Wurmehl, S.; Büchner, B.; Braden, M.

doi:10.1103/physrevb.90.144503

Cited by 25 publications

(40 citation statements)

References 44 publications

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“…The incommensurate peaks may arise from nesting of the outer hole or inner hole Fermi surface to the electron Fermi surfaces, which give slightly different incommensurability δ 1 and δ 2 , respectively, as seen in the experiment [ Fig. 1(c) and 1(e)] [22,23]. Figure 2(c) shows identical image of constant energy (E = 7 ± 1 meV) excitations for LiFe 0.88 Co 0.12 As.…”

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confidence: 66%

“…Based on ARPES measurements, the mismatched hole and electron Fermi surfaces should result in the incommensurate spin excitations at δ1 and δ2. (e) Positions of transverse incommensurate spin excitations of LiFeAs at E = 10 meV seen in the neutron scattering measurements [23]. (f) Commensurate spin excitations of LiFe0.88Co0.12As at E = 10 meV.…”

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confidence: 99%

“…The t 2g electrons near the Fermi level occupy the d xy and degenerate d xz /d yz orbitals. In the undoped state, low-energy spin excitations in LiFeAs are transversely incommensurate from the AF ordering wave vector of iron pnictides such as BaFe 2 As 2 [Fig 1(a) and [21][22][23]. When Co is doped into LiFeAs to form LiFe 1−x Co x As, superconductivity is gradually suppressed with increasing Co doping and vanishes near x = 0.14 [24], and the system becomes paramagnetic for higher Co-doping levels [ Fig.…”

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confidence: 99%

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Orbital Selective Spin Excitations and their Impact on Superconductivity ofLiFe1−xCoxAs

Yin

Wang

et al. 2016

Phys. Rev. Lett.

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We use neutron scattering to study spin excitations in single crystals of LiFe0.88Co0.12As, which is located near the boundary of the superconducting phase of LiFe1−xCoxAs and exhibits non-Fermi-liquid behavior indicative of a quantum critical point. By comparing spin excitations of LiFe0.88Co0.12As with a combined density functional theory (DFT) and dynamical mean field theory (DMFT) calculation, we conclude that wave-vector correlated low energy spin excitations are mostly from the dxy orbitals, while high-energy spin excitations arise from the dyz and dxz orbitals. Unlike most iron pnictides, the strong orbital selective spin excitations in LiFeAs family cannot be described by anisotropic Heisenberg Hamiltonian. While the evolution of low-energy spin excitations of LiFe1−xCoxAs are consistent with electron-hole Fermi surface nesting condition for the dxy orbital, the reduced superconductivity in LiFe0.88Co0.12As suggests that Fermi surface nesting conditions for the dyz and dxz orbitals are also important for superconductivity in iron pnictides.

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confidence: 66%

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confidence: 99%

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confidence: 99%

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Orbital Selective Spin Excitations and their Impact on Superconductivity ofLiFe1−xCoxAs

Yin

Wang

et al. 2016

Phys. Rev. Lett.

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“…Furthermore, even in K-overdoped BaFe 2 As 2 11 an anisotropic additional low-energy SRM remains visible ruling out that it just arises from the presence of quasi-static magnetic order. In Co-doped NaFeAs 12, 13 and in Na-doped BaFe 2 As 2 14 the low-energy features even dominate the magnetic scattering in the SC state while there is only an anisotropic shoulder in K-overdoped BaFe 2 As 2 11 and in LiFeAs 15 .…”

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Anisotropic resonance modes emerging in an antiferromagnetic superconducting state

Waßer

Lee

Kihou

et al. 2017

Sci Rep

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Two strong arguments in favor of magnetically driven unconventional superconductivity arise from the coexistence and closeness of superconducting and magnetically ordered phases on the one hand, and from the emergence of magnetic spin-resonance modes at the superconducting transition on the other hand. Combining these two arguments one may ask about the nature of superconducting spin-resonance modes occurring in an antiferromagnetic state. This problem can be studied in underdoped BaFe2 As2, for which the local coexistence of large moment antiferromagnetism and superconductivity is well established by local probes. However, polarized neutron scattering experiments are required to identify the nature of the resonance modes. In the normal state of Co underdoped BaFe2 As2 the antiferromagnetic order results in broad magnetic gaps opening in all three spin directions that are reminiscent of the magnetic response in the parent compound. In the superconducting state two distinct anisotropic resonance excitations emerge, but in contrast to numerous studies on optimum and over-doped BaFe2 As2 there is no isotropic resonance excitation. The two anisotropic resonance modes appearing within the antiferromagnetic phase are attributed to a band selective superconducting state, in which longitudinal magnetic excitations are gapped by antiferromagnetic order with sizable moment.

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“…The δKy indicates the expected transverse incommensurability. (d) The experimentally observed transverse incommensurate spin fluctuations and its energy dependence for SC and NSC LiFeAs (Qureshi et al, 2012a(Qureshi et al, , 2014bWang et al, 2012a). The δK is the observed transverse incommensurability.…”

Section: Evolution Of Spin Excitations In Iron Chalcogenides and Amentioning

confidence: 99%

Antiferromagnetic order and spin dynamics in iron-based superconductors

2015

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High-transition temperature (high-Tc) superconductivity in the iron pnictides/chalcogenides emerges from the suppression of the static antiferromagnetic order in their parent compounds, similar to copper oxides superconductors. This raises a fundamental question concerning the role of magnetism in the superconductivity of these materials. Neutron scattering, a powerful probe to study the magnetic order and spin dynamics, plays an essential role in determining the relationship between magnetism and superconductivity in high-Tc superconductors. The rapid development of modern neutron time-of-flight spectrometers allows a direct determination of the spin dynamical properties of iron-based superconductors throughout the entire Brillouin zone. In this review, we present an overview of the neutron scattering results on iron-based superconductors, focusing on the evolution of spin excitation spectra as a function of electron/hole-doping and isoelectronic substitution. We compare spin dynamical properties of iron-based superconductors with those of copper oxide and heavy fermion superconductors, and discuss the common features of spin excitations in these three families of unconventional superconductors and their relationship with superconductivity.

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Fine structure of the incommensurate antiferromagnetic fluctuations in single-crystalline LiFeAs studied by inelastic neutron scattering

Cited by 25 publications

References 44 publications

Orbital Selective Spin Excitations and their Impact on Superconductivity ofLiFe1−xCoxAs

Orbital Selective Spin Excitations and their Impact on Superconductivity ofLiFe1−xCoxAs

Anisotropic resonance modes emerging in an antiferromagnetic superconducting state

Antiferromagnetic order and spin dynamics in iron-based superconductors

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