Coexisting Itinerant and Localized Electrons

You, Yi-Zhuang; Weng, Zheng-Yu

doi:10.1007/978-3-319-11254-1_10

Cited by 3 publications

(3 citation statements)

References 178 publications

(252 reference statements)

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“…Answering this question is beyond the scope of the present work. Hence, we only introduce a promising approach that is based on an empirical two-fluid model for FeSCs [52,[61][62][63], to discuss this issue. In this model, the total electronic spectral weight is separated into two distinct parts.…”

Section: Discussionmentioning

confidence: 99%

Spin-Orbital-Intertwined Nematic State in FeSe

Lei

Zhao

et al. 2020

Phys. Rev. X

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The importance of the spin-orbit coupling (SOC) effect in Fe-based superconductors (FeSCs) has recently been under hot debate. Considering the Hund's coupling-induced electronic correlation, the understanding of the role of SOC in FeSCs is not trivial and is still elusive. Here, through a comprehensive study of 77 Se and 57 Fe nuclear magnetic resonance, a nontrivial SOC effect is revealed in the nematic state of FeSe. First, the orbital-dependent spin susceptibility, determined by the anisotropy of the 57 Fe Knight shift, indicates a predominant role from the 3dxy orbital, which suggests the coexistence of local and itinerant spin degrees of freedom (d.o.f.) in the FeSe. Then, we reconfirm that the orbital reconstruction below the nematic transition temperature (Tnem ∼ 90 K) happens not only on the 3dxz and 3dyz orbitals but also on the 3dxy orbital, which is beyond a trivial ferro-orbital order picture. Moreover, our results also indicate the development of a coherent coupling between the local and itinerant spin d.o.f. below Tnem, which is ascribed to a Hund's coupling-induced electronic crossover on the 3dxy orbital. Finally, due to a nontrivial SOC effect, sizable in-plane anisotropy of the spin susceptibility emerges in the nematic state, suggesting a spin-orbital-intertwined nematicity rather than simply spin-or orbital-driven nematicity. The present work not only reveals a nontrivial SOC effect in the nematic state but also sheds light on the mechanism of nematic transition in FeSe.

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Section: Discussionmentioning

confidence: 99%

Spin-Orbital-Intertwined Nematic State in FeSe

Lei

Zhao

et al. 2020

Phys. Rev. X

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“…The archetypal picture of magnetism displays an opposing dual character, i.e., itinerant electron magnetism with weak interactions and localized moments with strong Coulomb repulsions 1 . Understanding the behaviour of itinerant electrons in the presence of localized moments may shed light on nontrivial properties of correlated electron systems such as spin- or charge-density waves or superconductivity 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 , for which uniting both types of magnetism in one compound with clear electronic origins is necessary 22 27 . Experimentally, it is hard to clearly distinguish itinerant from localized moments in 3 d -based strongly-correlated electron materials like the copper-oxide superconductors 2 22 , despite the fact that they can be theoretically modeled 1 .…”

mentioning

confidence: 99%

“…Consequently, the experimentally observed smaller moment size in point compared to the expected theoretical saturation value [28] can be attributed either to the screening effect of itinerant electrons or to the frustration effect of localized spins. In addition, the nature of the antiferromagnetism or spin-density waves (SDWs) of iron-superconductors is still hotly debated as to whether the magnetic neutron excitations can be best described by the itinerant or localized picture [8,[15][16][17][18][19][20][21]. Disentangling these arguments necessitates the search for a model system that hosts clearly-defined itinerant and localized spins, thus permitting a complete understanding of their coupling mechanism.…”

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confidence: 99%

Distinct itinerant spin-density waves and local-moment antiferromagnetism in an intermetallic ErPd2Si2 single crystal

Cao

Wildes

et al. 2015

Sci Rep

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Identifying the nature of magnetism, itinerant or localized, remains a major challenge in condensed-matter science. Purely localized moments appear only in magnetic insulators, whereas itinerant moments more or less co-exist with localized moments in metallic compounds such as the doped-cuprate or the iron-based superconductors, hampering a thorough understanding of the role of magnetism in phenomena like superconductivity or magnetoresistance. Here we distinguish two antiferromagnetic modulations with respective propagation wave vectors at Q± = (H ± 0.557(1), 0, L ± 0.150(1)) and QC = (H ± 0.564(1), 0, L), where (H, L) are allowed Miller indices, in an ErPd2Si2 single crystal by neutron scattering and establish their respective temperature- and field-dependent phase diagrams. The modulations can co-exist but also compete depending on temperature or applied field strength. They couple differently with the underlying lattice albeit with associated moments in a common direction. The Q± modulation may be attributed to localized 4f moments while the QC correlates well with itinerant conduction bands, supported by our transport studies. Hence, ErPd2Si2 represents a new model compound that displays clearly-separated itinerant and localized moments, substantiating early theoretical predictions and providing a unique platform allowing the study of itinerant electron behavior in a localized antiferromagnetic matrix.

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