Electronically driven nematicity in FeSe Films on SrTiO3

Li, W.; Zhang, Y.; Lee, J. J.; Ding, Hong; Yi, Ming; Li, Z.; Deng, Peng; Chang, Kai; Mo, Sung‐Kwan; Hashimoto, M.; Lu, Da-Chuan; Chen, X.; Moore, Robert; Xue, Qi‐Kun; Shen, Zhi‐Xun

doi:10.48550/arxiv.1509.01892

Cited by 8 publications

(20 citation statements)

References 30 publications

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“…The small hole pockets centering M is attributed to d xy orbitals. All these Fermi surfaces are fully consistent with the experimental observations in the nematic phase [18,21,22]. Moreover, we show the band structure along the k y cut across the Dirac Nematicity-driven topology In normal states, the "k" and "k + Q" bands are degenerate at M point with opposite parities [25].…”

supporting

confidence: 88%

“…The former could be attributed to the spin-orbit coupling and the latter can be attributed to the nematicity [17,19,20]. The Dirac cone type of band dispersions around M point was observed in FeSe thin films thicker than 1 Unit Cell [21,22]. The corresponding Fermi surfaces around M are four propeller-like electron pockets.…”

mentioning

confidence: 91%

“…2(a). Moreover, the deep electron band intersects with the top hole band near the FL, forming a Dirac cone [21,22](the green circles in Fig. 2(a)).…”

mentioning

confidence: 99%

“…22 (k) = 11/22 + 2t11 x/y cosk x + 2t11 y/x cosk y + 4t11 xy cosk x cosk y + 2t 11 xx/yy cos2k x + 2t 11 yy/xx cos2k y +4t 11 xyy/xxy cosk x cos2k y + 4t 11 xxy/xyy cos2k x cosk y + 4t 11 xxyy cos2k x cos2k y , e 33/44/55 (k) = 33/44/55 + 2t 3/4/5 −4t 12 xy sink x sink y − 4t 12 xxy (sink x sin2k y − sin2k x sink y ) − 4t 44 xxyy sin2k x sin2k y , e 13/23 (k) = ±2it 13 y sink y/x ± 4it 13 xy cosk x/y sink y/x ± 2it 13 yy sin2k y/x ±4it 13 xxy cos2k x/y sink y/x ± 4it 13 xyy cosk x/y sin2k y/x , e 14/24 (k) = 2it 14 x sink x/y + 4it 14 xy sink x/y cosk y/x + 2it 14 xx sin2k x/y +4it 14 xxy sin2k x/y cosk y/x + 4it 14 xxyy sin2k x/y cos2k y/x , e 15/25 (k) = 2it 15 y sink y/x + 4it 15 xy cosk x/y sink y/x + 2it 15 yy sin2k y/x +4it 15 xxy cos2k x/y sink y/x + 4it 15 xyy cosk x/y sin2k y/x + 4it 15 xxyy cos2k x/y sin2k y/x , e 34 (k) = −4t 34 xyy (sink x sin2k y − sin2k x sink y ), e 35 (k) = 2t 35 x (cosk x − cosk y ) + 2t 35 xx (cos2k x − cosk 2y ) + 4t 35 xxy (cosk x cos2k y − cos2k x cosk y ), e 45 (k) = −4t 45 xy sink x sink y − 4t 45 xxyy sin2k x sink y . The corresponding hopping parameters are given in TableS1.…”

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confidence: 99%

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Nematic orders and nematicity-driven topological phase transition in FeSe

Wu,

Liang,

Fan

et al. 2016

Preprint

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We investigate nematic states in both bulk FeSe and FeSe thin films. It is found that their band structures and signature features that were observed in a variety of experiments can be perfectly explained by introducing the d-wave nematic orders that are required to have contributions from all t2g d-orbitals, which contradicts the conventional wisdom that the nematicity is simply driven by the orbital degeneracy between the dxz and dyz orbitals. These orders can be generated by the Coulomb interaction between the nearest neighbor Fe sites. In the presence of spin-orbital couplings, we predict that the nematic order can drive a topological quantum phase transition through a band inversion at the M point of the Brillouin zone to produce topologically protected edge states near the Fermi level. The prediction makes FeSe as a tunable system to integrate topological properties into high temperature superconductivity to realize Majorana related physics.

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supporting

confidence: 88%

mentioning

confidence: 91%

“…2(a). Moreover, the deep electron band intersects with the top hole band near the FL, forming a Dirac cone [21,22](the green circles in Fig. 2(a)).…”

mentioning

confidence: 99%

mentioning

confidence: 99%

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Nematic orders and nematicity-driven topological phase transition in FeSe

Wu,

Liang,

Fan

et al. 2016

Preprint

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“…Angle-Resolved Photoemission Spectroscopy (ARPES) measurements of FeSe [18][19][20][21][22][23][24][25][26][27] provide direct experimental access to the evolution of the electronic structure through T s , which can be linked to theoretical models of the underlying symmetry-breaking order. Most previous ARPES studies have paid particular attention to the electron pockets around the M point, and inferred a ∼50 meV splitting of d xz and d yz bands, similar to previous claims in NaFeAs [28] and Ba(Fe 1−x Co x ) 2 As 2 [29].…”

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confidence: 99%

Evidence for unidirectional nematic bond ordering in FeSe

et al. 2016

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The lifting of $d_{xz}$-$d_{yz}$ orbital degeneracy is often considered a hallmark of the nematic phase of Fe-based superconductors, including FeSe, but its origin is not yet understood. Here we report a high resolution Angle-Resolved Photoemission Spectroscopy study of single crystals of FeSe, accounting for the photon-energy dependence and making a detailed analysis of the temperature dependence. We find that the hole pocket undergoes a fourfold-symmetry-breaking distortion in the nematic phase below 90~K, but in contrast the changes to the electron pockets do not require fourfold symmetry-breaking. Instead, there is an additional separation of the existing $d_{xy}$ and $d_{xz/yz}$ bands - which themselves are not split within resolution. These observations lead us to propose a new scenario of "unidirectional nematic bond ordering" to describe the low-temperature electronic structure of FeSe, supported by a good agreement with 10-orbital tight binding model calculations

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Electronic Structure Properties in the Nematic Phases of FeSe

Liang

2015

Chinese Phys. Lett.

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We investigate the electronic structures of FeSe in the presence of different possible orders. We find that only ferro-orbital order (FO) and collinear antiferro-magnetism (C-AFM) can simultaneously induce splittings at Γ and M. Bicollinear antiferro-magnetism (B-AFM) and spin-orbit coupling (SOC) have very similar band structure on Γ-M near the Fermi level. The temperature insensitive splitting at Γ and the temperature dependent splitting at M observed in recent experiments can be explained by the d-wave bond nematic (dBN) order together with SOC. The recent observed Dirac cones and their temperature (T ) dependence in FeSe thin films can also be well explained by the dBN order with band renormalization. Their thickness-and cobalt-doping-dependent behaviors are the consequences of electron doping and reduction of Se height. All these suggest that the nematic order in FeSe system is the dBN order.

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Electronically driven nematicity in FeSe Films on SrTiO3

Cited by 8 publications

References 30 publications

Nematic orders and nematicity-driven topological phase transition in FeSe

Nematic orders and nematicity-driven topological phase transition in FeSe

Evidence for unidirectional nematic bond ordering in FeSe

Electronic Structure Properties in the Nematic Phases of FeSe

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