2020-01-31 · FeSe is an unusual FeSC that exhibits nematicity without long range magnetic order. On one hand it provides a unique opportunity to disentangle the effect of nematicity on the electronic structure from that of magnetism; while on the other it provides a test case to gauge whether the isolated long range nematic order is qualitatively similar to that of other FeSCs where the two orders are

ARPES: schematic Fermi surfaces of FeSe –3D Tetragonal phase: smaller pockets and band renormalisations. Nematic phase: the hole pocket distorts, one elongated electron pocket seen by ARPES. DFT calculation. One-ellipse effect preceding SDW in …

2017-05-05 · Thus the low temperature Fermi surface of FeSe as experimentally determined by ARPES consists of one elliptical hole pocket and one orthogonally-oriented peanut-shaped electron pocket. Our measurements clarify the long-standing controversies over the interpretation of ARPES measurements of FeSe. We report high resolution ARPES measurements of detwinned FeSe single crystals. The application of a mechanical strain is used to promote the volume fraction of one of the orthorhombic domains in the sample, which we estimate to be 80% detwinned. While the full structure of the electron pockets consisting of two crossed ellipses may be observed in the tetragonal phase at temperatures above 90 2015-04-16 · The ARPES results on FeSe single crystals reported so far give a basically consistent picture [32, 67, 68], as exemplified in figure 4.

For 2D films, interface interactions can play a critical role in determining the prevailing physics of the system. In the case of 1ML FeSe on SrTiO3, interfacial electron-phonon (e-ph) coupling greatly increases its superconducting Tc over its bulk counterpart. We report high resolution angle-resolved photo-emission spectroscopy (ARPES) measurements of detwinned FeSe single crystals. The application of a mechanical strain is used to promote the volume 2019-10-02 · However, correlations strongly renormalize the bands compared to electronic structure calculations, and there is no evidence for the expected bulk band inversion. We present here a comprehensive angle resolved photoemission (ARPES) study of FeSeTe as function of photon energies ranging from 15 - 100 eV. 2017-05-05 · Thus the low temperature Fermi surface of FeSe as experimentally determined by ARPES consists of one elliptical hole pocket and one orthogonally-oriented peanut-shaped electron pocket.

On one hand it provides a unique opportunity to disentangle the effect of nematicity on the electronic structure from that of magnetism; while on the other it provides a test case to gauge whether the isolated long range nematic order is qualitatively similar to that of other FeSCs where the two orders are We present a systematic angle-resolved photoemission spectroscopy study of the superconducting gap in FeSe.

The first ARPES study on single-layer FeSe/STO films has provided key insights into the electronic origin of superconductivity in this system. A phase diagram and

By probing detwinned crystals with different linear polarizations of their pulsed laser system (250 fs time resolution), they can selectively observe xz and yz orbital electrons. This book mainly focuses on the study of the high-temperature superconductor Bi2Sr2CaCu2O8+δ (Bi2212) and single-layer FeSe film grown on SrTiO3 (STO) substrate by means of angle-resolved photoemission spectroscopy (ARPES).

In this Nature paper, T. Shimojima (RIKEN CEMS) et al. use time-resolved ARPES to visualize the ultrafast dynamics of electronic nematicity in FeSe. By probing detwinned crystals with different linear polarizations of their pulsed laser system (250 fs time resolution), they can selectively observe xz and yz orbital electrons.

A phase diagram and The first ARPES study on single-layer FeSe/STO films has provided key insights substrate by means of angle-resolved photoemission spectroscopy (ARPES).

The gap function is determined in a full Brillouin zone including all Fermi surfaces and kz-dependence. We find significant anisotropy of the superconducting gap in all momentum directions. While the in-plane anisotropy can be explained by both, nematicity-induced pairing anisotropy and We have performed in-situ angle-resolved photoemission spectroscopy measurements of cesium(Cs)-deposited FeSe thin films on SrTiO 3. We found that Cs deposition enables heavily electron doping into the FeSe layer.
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The application of a mechanical strain is used to promote the volume fraction of one of the orthorhombic domains in the sample, which we estimate to be 80% detwinned. While the full structure of the electron pockets consisting of two crossed ellipses may be observed in the tetragonal phase at temperatures above 90 In this paper, to our knowledge, we report the first observation of an insulator–superconductor crossover in the iron-based superconductors by performing systematic angle-resolved photoemission (ARPES) measurements on the single-layer FeSe/SrTiO 3 films at various carrier concentrations. At a very low carrier concentration, the spectral The observation of replica bands in single-unit-cell FeSe on SrTiO3 (STO)(001) by angle-resolved photoemission spectroscopy (ARPES) has led to the conjecture that the coupling between FeSe Phase diagram of FeSe 1 − x S x and the suppression of electronic correlations by S substitution. (a) The ARPES map of the high-symmetry cut through top of the Brillouin zone for the tetragonal phase of FeSe 1 − x S x (x = 0, 0.18, 1) at 56–69 eV, together with a calculated slice for FeS in (b).
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2017-10-23 · We report high resolution angle-resolved photo-emission spectroscopy (ARPES) measurements of detwinned FeSe single crystals. The application of a mechanical strain is used to promote the volume fraction of one of the orthorhombic domains in the sample, which we estimate to be detwinned.

Surprisingly, the Tc of a single layer of FeSe film grown epitaxially on the SrTiO 3 substrate is enhanced to over 55K. We perform in-situ synchrotron-based MBE/ARPES experiment to understand how the transition temperature can be enhanced from the bulk superconducting transition temperature (Tc) of 8K at this 1UC FeSe/STO … 2017-02-10 Combining Angle resolved photoelectron spectroscopy (ARPES) and a μ-focused Laser, we have performed scanning ARPES microscopy measurements of the domain population within the nematic phase of FeSe single crystals.We are able to demonstrate a variation of the domain population density on a scale of a few 10 μm while constraining the upper limit of the single domain size to less than 5 μm. 2014-12-30 Here we present the influence of different STO surface terminations and photon energy dependent ARPES results which help to clarify the role of the substrate in the monolayer FeSe system. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division under contract DE-AC02-76SF00515. 2017-10-20 Here, we report high resolution angle resolved photoemission spectroscopy (ARPES) results which reveal an unexpected and unique characteristic of the 1UC FeSe/STO system: each energy band of the FeSe film is almost exactly replicated at a fixed energy separation.