Orbital characters of three-dimensional Fermi surfaces in Eu2−xSrxNiO4as probed by soft-x-ray angle-resolved photoemission spectroscopy

Abstract The isovalent-substituted iron pnictide compound SrFe2(As1−xPx)2 exhibits multiple evidence for nodal superconductivity via various experimental probes, such as the penetration depth, nuclear magnetic resonance and specific heat measurements. The direct identification of the nodal superconducting (SC) gap structure is challenging, partly because the presence of nodes is not protected by symmetry but instead caused by an accidental sign change of the order parameter, and also because of the three-dimensionality of the electronic structure. We have studied the SC gaps of SrFe2(As0.65P0.35)2 in three-dimensional momentum space by synchrotron and laser-based angle-resolved photoemission spectroscopy. The three hole Fermi surfaces (FSs) at the zone center have SC gaps with different magnitudes, whereas the SC gaps of the electron FSs at the zone corner are almost isotropic and kz-independent. As a possible nodal SC gap structure, we propose that the SC gap of the outer hole FS changes sign around the Z-X [(0, 0, 2π) − (π, π, 2π)] direction.

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Fermi surfaces and p−d hybridization in the diluted magnetic semiconductor Ba1−xKx(Zn1−yMny)2As2 studied by soft x-ray angle-resolved photoemission spectroscopy

Physical Review B ◽

10.1103/physrevb.92.235120 ◽

2015 ◽

Vol 92 (23) ◽

Cited By ~ 20

Author(s):

H. Suzuki ◽

G. Q. Zhao ◽

K. Zhao ◽

B. J. Chen ◽

M. Horio ◽

...

Keyword(s):

Diluted Magnetic Semiconductor ◽

Magnetic Semiconductor ◽

Photoemission Spectroscopy ◽

Fermi Surfaces ◽

X Ray ◽

Angle Resolved Photoemission Spectroscopy ◽

Diluted Magnetic

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Soft X-ray angle-resolved photoemission with micro-positioning techniques for metallic V2O3

Journal of Synchrotron Radiation ◽

10.1107/s1600577515003707 ◽

2015 ◽

Vol 22 (3) ◽

pp. 776-780 ◽

Cited By ~ 4

Author(s):

Hidenori Fujiwara ◽

Takayuki Kiss ◽

Yuki K. Wakabayashi ◽

Yoshito Nishitani ◽

Takeo Mori ◽

...

Keyword(s):

Three Dimensional ◽

Polar Angle ◽

Sample Surface ◽

Photoemission Spectroscopy ◽

High Quality ◽

X Ray ◽

Angle Resolved Photoemission Spectroscopy ◽

Position Dependence ◽

Working Distance ◽

Band Mapping

Soft X-ray angle-resolved photoemission has been performed for metallic V2O3. By combining a microfocus beam (40 µm × 65 µm) and micro-positioning techniques with a long-working-distance microscope, it has been possible to observe band dispersions from tiny cleavage surfaces with a typical size of several tens of µm. The photoemission spectra show a clear position dependence, reflecting the morphology of the cleaved sample surface. By selecting high-quality flat regions on the sample surface, it has been possible to perform band mapping using both photon-energy and polar-angle dependences, opening the door to three-dimensional angle-resolved photoemission spectroscopy for typical three-dimensional correlated materials where large cleavage planes are rarely obtained.

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Layer-resolved many-electron interactions in delafossite PdCoO2 from standing-wave photoemission spectroscopy

Communications Physics ◽

10.1038/s42005-021-00643-y ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Qiyang Lu ◽

Henrique Martins ◽

Juhan Matthias Kahk ◽

Gaurab Rimal ◽

Seongshik Oh ◽

...

Keyword(s):

Charge Transfer ◽

Standing Wave ◽

Three Dimensional ◽

Photoemission Spectroscopy ◽

Electronic Coupling ◽

Many Body ◽

X Ray ◽

Charge Transfer Excitons ◽

Many Body Interactions ◽

Electron Interactions

AbstractWhen a three-dimensional material is constructed by stacking different two-dimensional layers into an ordered structure, new and unique physical properties can emerge. An example is the delafossite PdCoO2, which consists of alternating layers of metallic Pd and Mott-insulating CoO2 sheets. To understand the nature of the electronic coupling between the layers that gives rise to the unique properties of PdCoO2, we revealed its layer-resolved electronic structure combining standing-wave X-ray photoemission spectroscopy and ab initio many-body calculations. Experimentally, we have decomposed the measured VB spectrum into contributions from Pd and CoO2 layers. Computationally, we find that many-body interactions in Pd and CoO2 layers are highly different. Holes in the CoO2 layer interact strongly with charge-transfer excitons in the same layer, whereas holes in the Pd layer couple to plasmons in the Pd layer. Interestingly, we find that holes in states hybridized across both layers couple to both types of excitations (charge-transfer excitons or plasmons), with the intensity of photoemission satellites being proportional to the projection of the state onto a given layer. This establishes satellites as a sensitive probe for inter-layer hybridization. These findings pave the way towards a better understanding of complex many-electron interactions in layered quantum materials.

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Aging of the surface of an Al-Cr-Fe approximant phase in ambient conditions: chemical composition and physical properties

MRS Proceedings ◽

10.1557/proc-805-ll8.8 ◽

2003 ◽

Vol 805 ◽

Cited By ~ 2

Author(s):

D. Veys ◽

P. Weisbecker ◽

V. Fournée ◽

B. Domenichini ◽

S. Weber ◽

...

Keyword(s):

Chemical Composition ◽

Mass Spectroscopy ◽

Electrochemical Behavior ◽

Stable State ◽

Photoemission Spectroscopy ◽

Atmospheric Conditions ◽

Electrical Model ◽

Ambient Conditions ◽

X Ray ◽

Angle Resolved Photoemission Spectroscopy

ABSTRACTWe have investigated the surface properties of quasicrystalline and approximant phases in the Al-(Cu)-Cr-Fe system upon aging in ambient conditions. We found that some of these properties (like the electrochemical behavior, wetting or friction) slowly evolves with the length of exposure to normal atmospheric conditions, reaching a stable state only after several days. This report essentially focuses on one of these alloys, an Al65Cr27Fe8 approximant phase with g-brass structure. In a first part, we describe the effect of aging on the electrochemical behavior of this alloy and we propose an interpretation based on a simple electrical model of the oxidized surface. In a second part, we present a model describing the surface as a stacking of several layers (oxides, oxy-hydroxides, contamination) whose thickness evolves with time. The model is supported by X-ray reflectivity, angle-resolved photoemission spectroscopy and secondary neutral mass spectroscopy measurements.

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Dirac nodal surfaces and nodal lines in ZrSiS

Science Advances ◽

10.1126/sciadv.aau6459 ◽

2019 ◽

Vol 5 (5) ◽

pp. eaau6459 ◽

Cited By ~ 26

Author(s):

B.-B. Fu ◽

C.-J. Yi ◽

T.-T. Zhang ◽

M. Caputo ◽

J.-Z. Ma ◽

...

Keyword(s):

Photoemission Spectroscopy ◽

Dirac Fermions ◽

Fermi Surfaces ◽

Angle Resolved Photoemission Spectroscopy ◽

Nodal Lines ◽

Nodal Points ◽

Different Dimensions ◽

Topological Semimetals ◽

Symmetry Protected ◽

Nodal Surfaces

Topological semimetals are characterized by symmetry-protected band crossings, which can be preserved in different dimensions in momentum space, forming zero-dimensional nodal points, one-dimensional nodal lines, or even two-dimensional nodal surfaces. Materials harboring nodal points and nodal lines have been experimentally verified, whereas experimental evidence of nodal surfaces is still lacking. Here, using angle-resolved photoemission spectroscopy (ARPES), we reveal the coexistence of Dirac nodal surfaces and nodal lines in the bulk electronic structures of ZrSiS. As compared with previous ARPES studies on ZrSiS, we obtained pure bulk states, which enable us to extract unambiguously intrinsic information of the bulk nodal surfaces and nodal lines. Our results show that the nodal lines are the only feature near the Fermi level and constitute the whole Fermi surfaces. We not only prove that the low-energy quasiparticles in ZrSiS are contributed entirely by Dirac fermions but also experimentally realize the nodal surface in topological semimetals.

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