Coupling of the As<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>A</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mi>g</mml:mi></mml:mrow></mml:msub></mml:math>phonon to magnetism in iron pnictides

García-Martínez, N.A.; Valenzuela, B.; Ciuchi, S.; Cappelluti, E.; Calderón, M. J.; Bascones, Elena

doi:10.1103/physrevb.88.165106

Cited by 30 publications

(45 citation statements)

References 64 publications

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“…It is found that the magnetic phase is able to induce a Raman intensity in the B 1g Raman polarisation due to the C 4 symmetry breaking but the intensity is very sensitive to the way in which the coupling between the electrons and the phonons is introduced. With similar symmetry arguments, a finite Te-phonon intensity in the B 2g polarisation was predicted to appear in the double stripe magnetic state of FeTe [268].…”

Section: Anisotropy and The Spin-orbital-lattice Entanglementmentioning

confidence: 87%

“…In Ref. [268] the Raman response is evaluated in the non-magnetic and in the magnetic states. It is found that the magnetic phase is able to induce a Raman intensity in the B 1g Raman polarisation due to the C 4 symmetry breaking but the intensity is very sensitive to the way in which the coupling between the electrons and the phonons is introduced.…”

Section: Anisotropy and The Spin-orbital-lattice Entanglementmentioning

confidence: 99%

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Magnetic interactions in iron superconductors: A review

Bascones

Valenzuela

Calderón

2015

Comptes Rendus. Physique

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High temperature superconductivity in iron pnictides and chalcogenides emerges when a magnetic phase is suppressed. The multi-orbital character and the strength of correlations underlie this complex phenomenology, involving magnetic softness and anisotropies, with Hund's coupling playing an important role. We review here the different theoretical approaches used to describe the magnetic interactions in these systems. We show that taking into account the orbital degree of freedom allows us to unify in a single phase diagram the main mechanisms proposed to explain the (π, 0) order in iron pnictides: the nesting-driven, the exchange between localized spins, and the Hund induced magnetic state with orbital differentiation. Comparison of theoretical estimates and experimental results helps locate the Fe superconductors in the phase diagram. In addition, orbital physics is crucial to address the magnetic softness, the doping dependent properties, and the anisotropies.

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Section: Anisotropy and The Spin-orbital-lattice Entanglementmentioning

confidence: 87%

Section: Anisotropy and The Spin-orbital-lattice Entanglementmentioning

confidence: 99%

Magnetic interactions in iron superconductors: A review

Bascones

Valenzuela

Calderón

2015

Comptes Rendus. Physique

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“…In addition, using time-and angle-resolved photoemission spectroscopy, a strong modulation of the chemical potential by the coherent A 1g mode has been observed [16,17]. These observations demonstrate a significant coupling of the A 1g mode to both the electronic and the spin system, which is also the subject of recent theoretical investigations [13,18,19]. So far no quantitative information about the ultrafast structural motions of the Fe-As lattice has been available.…”

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confidence: 90%

Ultrafast Structural Dynamics of the Fe-Pnictide Parent CompoundBaFe2As2

Rettig

Ferrer

et al. 2015

Phys. Rev. Lett.

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Using femtosecond time-resolved x-ray diffraction we investigate the structural dynamics of the coherently excited A1g phonon mode in the Fe-pnictide parent compound BaFe2As2. The fluence dependent intensity oscillations of two specific Bragg reflections with distinctly different sensitivity to the pnictogen height in the compound allow us to quantify the coherent modifications of the Fe-As tetrahedra, indicating a transient increase of the Fe magnetic moments. By a comparison with timeresolved photoemission data we derive the electron-phonon deformation potential for this particular mode. The value of ∆µ/∆z = −(1.0 − 1.5) eV/Å is comparable with theoretical predictions and demonstrates the importance of this degree of freedom for the electron-phonon coupling in the Fe pnictides. In the Fe pnictides, the complex interplay of the electronic, spin, orbital/ising-nematic and lattice degrees of freedoms leads to the emergence of a complex phase diagram, including structural transitions, spin-density wave (SDW) phases and high-temperature superconductivity. These phases emerge for electron and hole doping, but also for isovalent doping and external pressure [1,2]. The electronic structure and the magnetic properties depend very sensitively on the exact shape and size of the Fe-As tetrahedra, where an important degree of freedom is the pnictogen height h above the Fe layers, which changes the Fe-As tetrahedra angle α (see Fig. 1(a)). A high sensitivity of the Fe magnetic moments on the pnictogen height with a rate of 6.8 µ B /Å has been predicted [3], signifying a strong magneto-structural coupling [2,4,5]. Similarly, an increase of the electron-phonon (e-ph) coupling strength was been found in calculations including magnetic ordering [6,7]. Indeed, a universal relation between the Fe-As tetrahedra angle and the superconducting critical temperature T c has been proposed for the Fe pnictides [2,8], underlining the importance of structural degrees of freedom in these compounds.The role of e-ph coupling for the mechanism of superconductivity in the Fe pnictides is still controversial. The average e-ph coupling constant has been found to be relatively weak both experimentally [9][10][11] and theoretically [7,12] with λ 0.35, insufficient to explain the high critical temperatures found in the pnictides in a conventional pairing scheme. However, due to the strong interplay of structural and magnetic degrees of freedom, a few phonon modes with enhanced magneto-structural coupling could still play an important role in the superconducting pairing mechanism [5,13].One such mode is the Raman active A 1g mode at the zone center corresponding to a displacement of the As ions perpendicular to the Fe layers with ω ≈ 22 meV ( Fig. 1(a)). This mode directly modulates the pnictogen height h and thereby the Fe-As tetrahedra angle α. Coherent excitation of this mode has recently been observed using femtosecond (fs) time-resolved optical spectroscopy [14], and time-resolved THz spectroscopy demonstrated a transient resurrection of the mag...

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“…In the regime where the topological Mott insulating QAH state was expected, a charge-modulated (CM) density wave phase has been found to be the ground state in Refs. [8][9][10][11][12]. The QAH state, on the other hand, is completely expelled from the quantum phase diagram.…”

Section: Introductionmentioning

confidence: 99%

Electronic instabilities of the extended Hubbard model on the honeycomb lattice from functional renormalization

Volpez¹,

Scherer²,

Scherer³

2016

Phys. Rev. B

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Interacting fermions on the half-filled honeycomb lattice with short-range repulsions have been suggested to host a variety of interesting many-body ground states, e.g., a topological Mott insulator. A number of recent studies of the spinless case in terms of exact diagonalization, the infinite density matrix renormalization group and the functional renormalization group, however, indicate a suppression of the topological Mott insulating phase in the whole range of interaction parameters. Here, we complement the previous studies by investigating the quantum many-body instabilities of the physically relevant case of spin-1/2 fermions with onsite, nearest-neighbor and second-nearestneighbor repulsion. To this end, we employ the multi-patch functional renormalization group for correlated fermions with refined momentum resolution observing the emergence of an antiferromagnetic spin-density wave and a charge-density wave for dominating onsite and nearest-neighbor repulsions, respectively. For dominating second-nearest neighbor interaction our results favor an ordering tendency towards a charge-modulated ground state over the topological Mott insulating state. The latter evades a stabilization as the leading instability by the additional onsite interaction.

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Coupling of the AsA1gphonon to magnetism in iron pnictides

Cited by 30 publications

References 64 publications

Magnetic interactions in iron superconductors: A review

Magnetic interactions in iron superconductors: A review

Ultrafast Structural Dynamics of the Fe-Pnictide Parent CompoundBaFe2As2

Electronic instabilities of the extended Hubbard model on the honeycomb lattice from functional renormalization

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