Lifting of<i>xz</i>/<i>yz</i>orbital degeneracy at the structural transition in detwinned FeSe

Shimojima, T.; Suzuki, Y.; Sonobe, Tadashi; Nakamura, Atsutomo; Sakano, M.; Omachi, Junko; Yoshioka, Kosuke; Kuwata‐Gonokami, Makoto; Ono, Kanta; Kumigashira, Hiroshi; Böhmer, Anna E.; Hardy, F.; Wolf, Thomas; Meingast, C.; Löhneysen, H. v.; Ikeda, Hiroaki; Ishizaka, K.

doi:10.1103/physrevb.90.121111

Cited by 233 publications

(327 citation statements)

References 29 publications

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“…Although the nature of the transition at T s in FeSe is not yet clear, angle-resolved photoemission spectroscopy (ARPES) measurements on FeSe have found a splitting of the d xz and d yz bands at the corner of the Brillouin zone below ∼110 K, [5][6][7] similar to one found in BaFe 2 As 2 , 8 suggesting orbital order. 9 Secondly, the onset temperature of superconductivity can be enhanced up to ∼37 K by application of pressure.…”

Section: 4mentioning

confidence: 90%

Anomalous Fermi surface in FeSe seen by Shubnikov–de Haas oscillation measurements

et al. 2014

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We have observed Shubnikov-de Haas oscillations in FeSe. The Fermi surface deviates significantly from predictions of band-structure calculations and most likely consists of one electron and one hole thin cylinder. The carrier density is in the order of 0.01 carriers/ Fe, an order-of-magnitude smaller than predicted. Effective Fermi energies as small as 3.6 meV are estimated. These findings call for elaborate theoretical investigations incorporating both electronic correlations and orbital ordering.

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Section: 4mentioning

confidence: 90%

Anomalous Fermi surface in FeSe seen by Shubnikov–de Haas oscillation measurements

et al. 2014

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“…We can now discuss the implications of our results to the interpretation of ARPES experiments in the nematicparamagnetic state, which takes place in the temperature range T SDW < T < T nem for unstrained samples and in the temperature range T SDW < T for detwinned samples [4][5][6][7][8][9][10][11][12] . The observed splitting of the E M1 doublet has been mostly attributed to an anisotropy in the onsite energies of the d xz and d yz orbitals (ferro-orbital order), which in our model is given by ϕ Γ = ϕ 1 .…”

Section: Comparison To First-principle Calculations and Arpes Exmentioning

confidence: 99%

“…Angle-resolved photo-emission spectroscopy (ARPES), being sensitive to the electronic energy-momentum dispersion 3 , is an attractive tool to probe how these distinct ordered states manifest themselves in the electronic spectrum [4][5][6][7][8][9][10][11][12] . However, the close proximity of the different electronic energy scales, together with the multi-orbital character of the band structure, render this task non-trivial 13 .…”

Section: Introductionmentioning

confidence: 99%

Distinguishing spin-orbit coupling and nematic order in the electronic spectrum of iron-based superconductors

Fernandes

Vafek

2014

Phys. Rev. B

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The low-energy electronic states of the iron-based superconductors are strongly affected by both spin-orbit coupling and, when present, by the nematic order. These two effects have different physical origins, yet they can lead to similar gap features in the electronic spectrum. Here we show how to disentangle them experimentally in the iron superconductors with one Fe plane per unit cell. Although the splitting of the low energy doublet at the Brillouin zone center (Γ-point) can be due to either the spin-orbit coupling or the nematic order, or both, the degeneracy of each of the doublet states at the zone corner (M -point) is protected by the space group symmetry even when spin-orbit coupling is taken into account. Therefore, any splitting at M must be due to lowering of the crystal symmetry, such as due to the nematic order. We further analyze a microscopic tight-binding model with two different contributions to the nematic order: dxz/dyz onsite energy anisotropy and the dxy hopping anisotropy. We find that a precise determination of the former, which has been widely used to characterize the nematic phase, requires a simultaneous measurement of the splittings of the Γ-point doublet and at the two low-energy M -point doublets. We also discuss the impact of twin domains and show how our results shed new light on ARPES measurements in the normal state of these materials.

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“…Besides, FeSe possesses an electronic nematic order after a tetragonal-to-orthorhombic structural transition at T s 90K [19][20][21][22] . Although the primary origin of this nematic order is still unclear [23][24][25][26][27][28][29][30][31][32][33][34] , neutron scattering measurements indicate the important role of spin degree of freedom 24,25 .…”

Section: Introductionmentioning

confidence: 99%

Possible nematic spin liquid in spin-1 antiferromagnetic system on the square lattice: Implications for the nematic paramagnetic state of FeSe

et al. 2017

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The exotic normal state of iron chalcogenide superconductor FeSe, which exhibits vanishing magnetic order and possesses an electronic nematic order, triggered extensive explorations of its magnetic ground state. To understand its novel properties, we study the ground state of a highly frustrated spin-1 system with bilinearbiquadratic interactions using unbiased large-scale density matrix renormalization group. Remarkably, with increasing biquadratic interactions, we find a paramagnetic phase between Néel and stripe magnetic ordered phases. We identify this phase as a candidate of nematic quantum spin liquid by the compelling evidences, including vanished spin and quadrupolar orders, absence of lattice translational symmetry breaking, and a persistent non-zero lattice nematic order in the thermodynamic limit. The established quantum phase diagram natually explains the observations of enhanced spin fluctuations of FeSe in neutron scattering measurement and the phase transition with increasing pressure. This identified paramagnetic phase provides a new possibility to understand the novel properties of FeSe.

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Lifting ofxz/yzorbital degeneracy at the structural transition in detwinned FeSe

Cited by 233 publications

References 29 publications

Anomalous Fermi surface in FeSe seen by Shubnikov–de Haas oscillation measurements

Anomalous Fermi surface in FeSe seen by Shubnikov–de Haas oscillation measurements

Distinguishing spin-orbit coupling and nematic order in the electronic spectrum of iron-based superconductors

Possible nematic spin liquid in spin-1 antiferromagnetic system on the square lattice: Implications for the nematic paramagnetic state of FeSe

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