Strong surface termination dependence of the electronic structure of polar superconductor LaFeAsO revealed by nano-ARPES

Sung Won Jung; Luke C Rhodes; Matthew D Watson; Daniil V Evtushinsky; Cephise Cacho; Saicharan Aswartham; Rhea Kappenberger; Sabine Wurmehl; Bernd Büchner; Timur K Kim

doi:10.1088/1367-2630/ac9d5e

Strong surface termination dependence of the electronic structure of polar superconductor LaFeAsO revealed by nano-ARPES

Sung Won Jung^*, Luke C Rhodes, Matthew D Watson, Daniil V Evtushinsky, Cephise Cacho, Saicharan Aswartham, Rhea Kappenberger, Sabine Wurmehl, Bernd Büchner, Timur K Kim^*

^*Corresponding author for this work

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

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Abstract

The electronic structures of the iron-based superconductors have been intensively studied by using angle-resolved photoemission spectroscopy (ARPES). A considerable amount of research has been focused on the LaFeAsO family, showing the highest transition temperatures, where previous ARPES studies have found much larger Fermi surfaces than bulk theoretical calculations would predict. The discrepancy has been attributed to the presence of termination-dependent surface states. Here, using photoemission spectroscopy with a sub-micron focused beam spot (nano-ARPES) we have successfully measured the electronic structures of both the LaO and FeAs terminations in LaFeAsO. Our data reveal very different band dispersions and core-level spectra for different surface terminations, showing that previous macro-focus ARPES measurements were incomplete. Our results give direct evidence for the surface-driven electronic structure reconstruction in LaFeAsO, including formation of the termination-dependent surface states at the Fermi level. This experimental technique, which we have shown to be very powerful when applied to this prototypical compound, can now be used to study various materials with different surface terminations.

Original language	English
Article number	113018
Number of pages	9
Journal	New Journal of Physics
Volume	24
Issue number	11
Early online date	10 Nov 2022
DOIs	https://doi.org/10.1088/1367-2630/ac9d5e
Publication status	Published - 10 Nov 2022

Keywords

Iron-based superconductors
Photoemission
Electronic structure
Polar surface

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@article{d0c3601c10e6451593ecb14671614dff,

title = "Strong surface termination dependence of the electronic structure of polar superconductor LaFeAsO revealed by nano-ARPES",

abstract = "The electronic structures of the iron-based superconductors have been intensively studied by using angle-resolved photoemission spectroscopy (ARPES). A considerable amount of research has been focused on the LaFeAsO family, showing the highest transition temperatures, where previous ARPES studies have found much larger Fermi surfaces than bulk theoretical calculations would predict. The discrepancy has been attributed to the presence of termination-dependent surface states. Here, using photoemission spectroscopy with a sub-micron focused beam spot (nano-ARPES) we have successfully measured the electronic structures of both the LaO and FeAs terminations in LaFeAsO. Our data reveal very different band dispersions and core-level spectra for different surface terminations, showing that previous macro-focus ARPES measurements were incomplete. Our results give direct evidence for the surface-driven electronic structure reconstruction in LaFeAsO, including formation of the termination-dependent surface states at the Fermi level. This experimental technique, which we have shown to be very powerful when applied to this prototypical compound, can now be used to study various materials with different surface terminations.",

keywords = "Iron-based superconductors, Photoemission, Electronic structure, Polar surface",

author = "Jung, {Sung Won} and Rhodes, {Luke C} and Watson, {Matthew D} and Evtushinsky, {Daniil V} and Cephise Cacho and Saicharan Aswartham and Rhea Kappenberger and Sabine Wurmehl and Bernd B{\"u}chner and Kim, {Timur K}",

note = "Funding: LCR acknowledges funding from the Royal Commission for the Exhibition of 1851. The work at IFW was supported by the Deutsche Forschungsgemeinschaft (DFG) through the Priority Program SPP1458. SA thanks the DFG for funding (AS 523∖4-1 & 523∖3-1).",

year = "2022",

month = nov,

day = "10",

doi = "10.1088/1367-2630/ac9d5e",

language = "English",

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journal = "New Journal of Physics",

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TY - JOUR

T1 - Strong surface termination dependence of the electronic structure of polar superconductor LaFeAsO revealed by nano-ARPES

AU - Jung, Sung Won

AU - Rhodes, Luke C

AU - Watson, Matthew D

AU - Evtushinsky, Daniil V

AU - Cacho, Cephise

AU - Aswartham, Saicharan

AU - Kappenberger, Rhea

AU - Wurmehl, Sabine

AU - Büchner, Bernd

AU - Kim, Timur K

N1 - Funding: LCR acknowledges funding from the Royal Commission for the Exhibition of 1851. The work at IFW was supported by the Deutsche Forschungsgemeinschaft (DFG) through the Priority Program SPP1458. SA thanks the DFG for funding (AS 523∖4-1 & 523∖3-1).

PY - 2022/11/10

Y1 - 2022/11/10

N2 - The electronic structures of the iron-based superconductors have been intensively studied by using angle-resolved photoemission spectroscopy (ARPES). A considerable amount of research has been focused on the LaFeAsO family, showing the highest transition temperatures, where previous ARPES studies have found much larger Fermi surfaces than bulk theoretical calculations would predict. The discrepancy has been attributed to the presence of termination-dependent surface states. Here, using photoemission spectroscopy with a sub-micron focused beam spot (nano-ARPES) we have successfully measured the electronic structures of both the LaO and FeAs terminations in LaFeAsO. Our data reveal very different band dispersions and core-level spectra for different surface terminations, showing that previous macro-focus ARPES measurements were incomplete. Our results give direct evidence for the surface-driven electronic structure reconstruction in LaFeAsO, including formation of the termination-dependent surface states at the Fermi level. This experimental technique, which we have shown to be very powerful when applied to this prototypical compound, can now be used to study various materials with different surface terminations.

AB - The electronic structures of the iron-based superconductors have been intensively studied by using angle-resolved photoemission spectroscopy (ARPES). A considerable amount of research has been focused on the LaFeAsO family, showing the highest transition temperatures, where previous ARPES studies have found much larger Fermi surfaces than bulk theoretical calculations would predict. The discrepancy has been attributed to the presence of termination-dependent surface states. Here, using photoemission spectroscopy with a sub-micron focused beam spot (nano-ARPES) we have successfully measured the electronic structures of both the LaO and FeAs terminations in LaFeAsO. Our data reveal very different band dispersions and core-level spectra for different surface terminations, showing that previous macro-focus ARPES measurements were incomplete. Our results give direct evidence for the surface-driven electronic structure reconstruction in LaFeAsO, including formation of the termination-dependent surface states at the Fermi level. This experimental technique, which we have shown to be very powerful when applied to this prototypical compound, can now be used to study various materials with different surface terminations.

KW - Iron-based superconductors

KW - Photoemission

KW - Electronic structure

KW - Polar surface

U2 - 10.1088/1367-2630/ac9d5e

DO - 10.1088/1367-2630/ac9d5e

M3 - Article

SN - 1367-2630

VL - 24

JO - New Journal of Physics

JF - New Journal of Physics

IS - 11

M1 - 113018

ER -

Strong surface termination dependence of the electronic structure of polar superconductor LaFeAsO revealed by nano-ARPES

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