First-principles study of magnetic frustration in FeSe epitaxial films on<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>SrTiO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>

Liu, Kai; Zhang, Bingjing; Lu, Zhong-Yi

doi:10.1103/physrevb.91.045107

Cited by 23 publications

(30 citation statements)

References 48 publications

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“…Presuming (based on bulk FeSe) that FeSe provides a charge-neutral 1UC overlayer, the van der Waals (vdW) interaction may play a significant role in the interlayer bonding. Liu et al 22 reported that the distance between the top Se atom of first unit cell and the TiO 2 termination plane of the substrate is about 5.56Å when accounting for the vdW interaction, which would be consistent with the reported experimental value 5.5Å 2 . With this value, d S =2.66Å.…”

Section: A Structure Of the Simulation Cellsupporting

confidence: 84%

“…20 Shanavas and Singh (SS) found that both O vacancies in the STO substrate and excess Fe over the monolayer can provide high levels of electron doping 21 . A somewhat different viewpoint arises from evidence that doped electrons accumulate at the interface was presented by Liu et al 22 Se vacancies were considered by Berlijn et al 23 , who observed unanticipated character of anion vacancies, behaving more as hole donors than electron donors.…”

Section: Introductionmentioning

confidence: 99%

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Electronic coupling between a FeSe monolayer film and SrTiO3 substrate

Huang

Pickett

2017

Phys. Rev. B

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Several experimental groups have reported superconductivity in single unit cell layers of FeSe on SrTiO3 and a few other substrates, with critical temperature Tc reports ranging up to 100 K, and a variety of theoretical work has been done. Here we examine more closely the interaction of a single FeSe layer with a TiO2 terminated SrTiO3(001) (STO) substrate. Several situations are analyzed: the underlying ideal interface, the effect of z-polarized longitudinal optic [LO(ẑ)] phonons in STO, electron doping of the STO substrate, substitution of Se by the bordering chalcogenides S and Te, and doping by adsorption of K on the FeSe surface. These results complement earlier studies of O and Se vacancies. The O py, py surface band of STO persists at the interface, and by sharing holes with hole pocket of FeSe it plays a part in the behavior around the interface, initially by determining the Fe Fermi level lineup with the STO bandgap. The LO(ẑ) mode causes strong band shifts around the interface but the strength of coupling to the Fe bands cannot be obtained with our methods. Adsorption of 25% K (one K per four Fe) fills the small O interface hole pocket and donates the rest of the electrons to the Fe hole pockets, filling them.

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Section: A Structure Of the Simulation Cellsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Electronic coupling between a FeSe monolayer film and SrTiO3 substrate

Huang

Pickett

2017

Phys. Rev. B

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“…Although this is a minimal representation of the substrate STO, our results reasonably reproduce previous calculations that use thicker STO substrates. 14,17,18,22 The planer lattice constant a is set to the STO parameter ∼3.9Å. The vertical heights of Fe and Se above the TiO 2 are relaxed in the CB-AFM state (as summarized in Ta- ble I of the Supplementary Information), and then held fixed during the spin-spiral calculations.…”

Section: Resultsmentioning

confidence: 99%

“…Although the energy difference between the CB-and CL-AFM states is found to be reduced by electron doping due to the substrate, the CL-AFM state remains more stable at reasonable doping levels. 14,17,22 Moreover, there is no experimental evidence for longrange magnetic order in either bulk or monolayer FeSe -recent inelastic neutron scattering experiments 24 have found that CB-AFM and CL-AFM correlations coexist even at low excitation energies in the bulk -suggesting that a quantum paramagnetic state with strong fluctuations between the CB-AFM and CL-AFM states might also exist in the monolayer system. Furthermore, it has been suggested that a nematic paramagnetic state resembling the observed bulk FeSe nematic state is a result of a near degeneracy between the CB-AFM and CL-AFM states.…”

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confidence: 99%

Magnetic fluctuations in single-layer FeSe

Shishidou¹,

Agterberg²,

Weinert³

2018

Commun Phys

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The paramagnetic nature of monolayer FeSe films is investigated via first-principles spin-spiral calculations. Although the (π,π) collinear antiferromagnetic (CL-AFM) mode -the prevailing spin fluctuation mode relevant to most iron-based superconductors -is lowest in energy, the spin-wave energy dispersion E(q) is found to be extremely flat over a large region of the two-dimensional Brillouin zone centered at the checkerboard antiferromagnetic (CB-AFM) q=0 configuration, giving rise to a sharp peak in the spin density of states. Considering the paramagnetic state as an incoherent average over spin-spiral states, we find that resulting electronic band states around the Fermi level closely resemble the bands of the CB-AFM configuration -not the CL-AFM one -and thus providing a natural explanation of the angle-resolved photoemission observations. The presence of the SrTiO3(001) substrate, both with and without interfacial oxygen vacancies, is found to reduce the energy difference between the CB-AFM and CL-AFM states and hence enhance the CB-AFMlike fluctuations. These results suggest that CB-AFM fluctuations play a more important role than previously thought. arXiv:1708.07868v2 [cond-mat.mtrl-sci]

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“…However, no Fermi surface reconstruction induced by spin density wave was observed in monolayer FeSe/STO but in mutlilayer FeSe/STO in ARPES experiments [12]. The recent first-principles calculations proposed that the magnetic order was strongly frustrated in monolayer FeSe/STO with 2J 2 ≈ |J 1 | [51]. Another issue is the sign of J 1 .…”

Section: The Effective Pairing Interactionsmentioning

confidence: 97%

Topological superconducting states in monolayerFeSe/SrTiO3

Hao

Shen

2015

Phys. Rev. B

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The monolayer FeSe with a thickness of one unit cell grown on a single-crystal SrTiO 3 substrate (FeSe/STO) exhibits striking high-temperature superconductivity with transition temperature T c over 65 K reported by recent experimental measurements. In this work, through analyzing the distinctive electronic structure, and providing systematic classification of the pairing symmetry, we find that both sand p-wave pairing with odd parity give rise to topological superconducting states in monolayer FeSe, and the exotic properties of s-wave topological superconducting states have close relations with the unique nonsymmorphic lattice structure which induces the orbital-momentum locking. Our results indicate that the monolayer FeSe could be in the topological nontrivial s-wave superconducting states if the relevant effective pairing interactions are dominant in comparison with other candidates.

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First-principles study of magnetic frustration in FeSe epitaxial films onSrTiO3

Cited by 23 publications

References 48 publications

Electronic coupling between a FeSe monolayer film and SrTiO3 substrate

Electronic coupling between a FeSe monolayer film and SrTiO3 substrate

Magnetic fluctuations in single-layer FeSe

Topological superconducting states in monolayerFeSe/SrTiO3

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