Anisotropic magnetic excitations and incipient Néel order in 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Ba</mml:mi><mml:msub><mml:mrow><mml:mo>(</mml:mo><mml:msub><mml:mi>Fe</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Mn</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:mo>)</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>As</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>

Garcia, F. A.; Ivashko, Oleh; McNally, Daniel; Das, Lakshmi Kanta; Piva, M. M.; Adriano, C.; Pagliuso, P. G.; Chang, J.; Schmitt, Thorsten; Monney, Claude

doi:10.1103/physrevb.99.115118

Cited by 15 publications

(23 citation statements)

References 39 publications

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“…Figure 2a, b summarize the Fe L-edge X-ray Absorption Spectroscopy (XAS) data for bulk FeSe (FeSe hereafter) and monolayer FeSe (FeSe/STO hereafter), respectively. The XAS of FeSe resembles the spectra previously obtained from cleaved Fe pnictides crystals with Fe in a 2+ oxidation state and embedded in a metal environment 10,11,13,15,16 . The XAS of FeSe/STO has an additional peak at higher energy, which could originate from new interfacial valence states induced by hybridization with orbitals of the STO substrate.…”

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confidence: 65%

“…Inelastic neutron scattering (INS) is currently unable to probe single atomic layers, and other light scattering techniques, such as Raman and optical spectroscopy, cannot disentangle the signals from the substrate, the FeSe layer, and the interface between the two. On this front, recent advances in Resonant Inelastic X-ray Scattering (RIXS) have allowed the detection of spin excitations in Fe-based superconductors, producing complementary information to INS [10][11][12][13][14][15][16][17][18] . The signal enhancement and sensitivity to electronic excitations that is afforded by resonant photoexcitation render RIXS a prime technique for investigating ultrathin materials.…”

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confidence: 99%

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Evolution of spin excitations from bulk to monolayer FeSe

et al. 2021

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In ultrathin films of FeSe grown on SrTiO3 (FeSe/STO), the superconducting transition temperature Tc is increased by almost an order of magnitude, raising questions on the pairing mechanism. As in other superconductors, antiferromagnetic spin fluctuations have been proposed to mediate SC making it essential to study the evolution of the spin dynamics of FeSe from the bulk to the ultrathin limit. Here, we investigate the spin excitations in bulk and monolayer FeSe/STO using resonant inelastic x-ray scattering (RIXS) and quantum Monte Carlo (QMC) calculations. Despite the absence of long-range magnetic order, bulk FeSe displays dispersive magnetic excitations reminiscent of other Fe-pnictides. Conversely, the spin excitations in FeSe/STO are gapped, dispersionless, and significantly hardened relative to its bulk counterpart. By comparing our RIXS results with simulations of a bilayer Hubbard model, we connect the evolution of the spin excitations to the Fermiology of the two systems revealing a remarkable reconfiguration of spin excitations in FeSe/STO, essential to understand the role of spin fluctuations in the pairing mechanism.

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confidence: 65%

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confidence: 99%

Evolution of spin excitations from bulk to monolayer FeSe

et al. 2021

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“…Spin dynamics in the FeSCs not only contain information on their magnetic interactions, but also provide clues regarding the size of the fluctuating magnetic moment (seen within timescale of the experimental probe), which in turn reflects the system's degree of itinerancy/localization [40][41][42]. While spin dynamics in FeSCs and related compounds are typically 075112-2 investigated using inelastic neutron scattering (INS) [42][43][44], resonant inelastic x-ray scattering (RIXS) has emerged as a useful complementary probe [45][46][47][48][49][50][51][52][53][54][55]. Since NaFeAs and NaFe 0.5 Cu 0.5 As exhibit significant similarities in their crystal and magnetic structures, a comparison of the spin dynamics in the two systems may provide insights for understanding the magnetism in the FeSCs.…”

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confidence: 99%

Spin dynamics in NaFeAs and NaFe0.53Cu0.47As probed by resonant inelastic x-ray scattering

et al. 2021

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The parent compounds of iron-based superconductors are magnetically ordered bad metals, with superconductivity appearing near a putative magnetic quantum critical point. The presence of both Hubbard repulsion and Hund's coupling leads to rich physics in these multiorbital systems, and motivated descriptions of magnetism in terms of itinerant electrons or localized spins. The NaFe 1−x Cu x As series consists of magnetically ordered bad metal (x = 0), superconducting (x ≈ 0.02) and magnetically ordered semiconducing/insulating (x ≈ 0.5) phases, providing a platform to investigate the connection between superconductivity, magnetism and electronic correlations. Here we use x-ray absorption spectroscopy and resonant inelastic x-ray scattering to study the valence state of Fe and spin dynamics in two NaFe 1−x Cu x As compounds (x = 0 and 0.47). We find that magnetism in both compounds arises from Fe 2+ atoms, and exhibits underdamped dispersive spin waves in their respective ordered states. The dispersion of spin excitations in NaFe 0.53 Cu 0.47 As is consistent with being quasi-one-dimensional. Compared to NaFeAs, the band top of spin waves in NaFe 0.53 Cu 0.47 As is slightly softened with significantly more spectral weight of the spin excitations. Our results indicate the spin dynamics in NaFe 0.53 Cu 0.47 As arise from localized magnetic moments and suggest the iron-based superconductors are proximate to a correlated insulating state with localized iron moments.

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“…Black squares and blue circles mark the data from Ref. [35] and red stars mark the data for our samples, as determined from resistivity measurements [34,36,37]. The investigated samples are indicated by black arrows.…”

Section: Methodsmentioning

confidence: 99%

Orbital localization and the role of the Fe and As $4p$ orbitals in BaFe$_{2}$As$_{2}$ probed by XANES

de Figueiredo,

Cantarino,

Neto

et al. 2021

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The polarization dependence of the near edge x-ray absorption spectroscopy (XANES) is an element specific probe to the real space distribution of the density of unoccupied states in solid state materials. In this work, we present Fe and As K-edge experiments of Ba(Fe 1−x M x ) 2 As 2 (M = Mn, Co and x = 0.0 and 0.08). The experiments reveal a strong polarization dependence of the probed XANES spectra, which concerns mainly an increase of the intensity of electronic transitions when the beam polarization is set out of the samples ab crystallographic plane. The results show that states with p z orbital character dominate the density of unoccupied states close to the Fermi level. Partial substitution of Fe by Co is shown to decrease the intensity anisotropy, suggesting that Co promotes electronic transfer preferentially to states with p z orbital character. On the other hand, Mn substitution causes the increase of the spectra p z orbital anisotropy, which is proposed to take place by means of an enhanced local Fe3d4p mixing, unveiling the role of Fe4p states in the localization of the Fe3d orbitals. Moreover, by comparing our results to previous experiments, we identify the relative mixing between Fe and the pnictide 4p x,y,z orbitals as a clear divide between the electronic properties of iron arsenides and selenides. Our conclusions are supported by multiple scattering theory calculations of the XANES spectra and by quantum chemistry calculations of Fe coordination electronic structure.

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Anisotropic magnetic excitations and incipient Néel order in Ba(Fe1−xMnx)2As2

Cited by 15 publications

References 39 publications

Evolution of spin excitations from bulk to monolayer FeSe

Evolution of spin excitations from bulk to monolayer FeSe

Spin dynamics in NaFeAs and NaFe0.53Cu0.47As probed by resonant inelastic x-ray scattering

Orbital localization and the role of the Fe and As $4p$ orbitals in BaFe$_{2}$As$_{2}$ probed by XANES

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