Angle-resolved Photoemission Spectroscopy

The Electronic structure of operando Micro-/Nano-Devices beamline specializes in angle-resolved photoemission spectroscopy (ARPES). Specifically designed with a soft X-ray energy range and a sub-micron to nano-scale beam spot, this beamline excels at probing the electronic structure of buried interfacial states and functional micro-nano devices in operando.

Overview

The beamline is sourced by an elliptically polarizing undulator (EPU63). A plane mirror M1 collects the diverging beam from the undulator and deflects the beam by 2° to reduce the heat load and cut off the high energy X-rays. The monochromator is Plane Grating Monochromator type, consisting a plane mirror M2 and three different variable line spacing (VLS) gratings. The monochromator energy-disperses X-rays, which is then focused vertically by the VLS gratings. Monochromatized X-ray beam is switchable into two branches by the ellipsoidal mirror M3 which also does the horizontal focus to the exist slit. At Branch A, X-ray beam is refocused by a KB mirror set to a sub-micro size. At Branch B, X-ray beam is refocused by a ZP to ~100 nm size in the nano-ARPES endstation. As a secondary choice, a small KB mirror set is planned to focus X-ray beam to ~100 nm in the nano-ARPES endstation.

Key Performance

Key Performance

Overview

Branch A is a SX-ARPES endstation with the X-ray beam energy ranging from 45 eV to 1000 eV. Equipped with a DFS30 analyzer from Scientia Omicron and a VLEED spin detector, this endstation is designed to measure both the electronic structure and the spin structure of quantum materials.  

I. Loadlock 

  Up to 20 samples can be loaded (flag-type sample plate)

II. Prepare chamber

  sample can be heated upto 1000 K;

  Argon sputtering;

  6 evaporator positions available once requested;

  ozone cleaning;    

III. Analysis chamber

　gold evaporator; 

    alkali metal doser;

    In-situ 4 electron leads on the sample position for   gating or straining use special designed sample plate;

    absorption spectroscopy measurements.

B-Branch: Nano-ARPES

ZP-Nano-ARPES

Overview

Branch B is a Nano-ARPES endstation. Two optical techniques are used separately to achieve ~ 100 nm beam size: the ZP-nano-ARPES and the KB-nano-ARPES. Both equipped with a DFS30 analyzer from Scientia Omicron. The energy of the zone plate chosen for the ZP-nano-ARPES is 100 eV and 150 eV. And the beam energy accessible for the KB-nano-ARPES is 45 eV~ 300 eV. Except for the optical method, all the other parameters are similar for the two endstations.

I. Loadlock 

  up to 12 samples can be loaded (flag-type sample plate)

II. Transfer chamber

  sample can be heated upto 1000 K;

  Argon sputtering;

  alkali metal doser;

  2 evaporator positions available once requested;  

III. Analysis chamber

  in situ 4 electron leads on the sample position for gating or straining use special designed sample plate;

Key Performance

Scientific Scope 1： Reducing the beam spot size to sub-micron and nanoscale levels enables the direct visualization of emergent quantum phenomena. This capability is critical for probing micro-scale phase separation in metal-insulator transitions and iron-based superconductors. Furthermore, it allows for the study of low-dimensional materials, particularly twisted systems like graphene and transition metal dichalcogenides, where nanoscale moiré patterns host novel correlated states. Finally, nanoscale beams are indispensable for resolving the electronic structure within operational sub-micron devices, bridging the gap between macroscopic measurement and nanoscale function.

Scientific Scope 2： The use of soft X-ray photons provides enhanced bulk sensitivity and elemental specificity compared to ultraviolet light. This enables the detection of bulk electronic states and allows researchers to distinguish them from surface states. Furthermore, the technique is well-suited for probing the electronic structure of buried interfaces, such as two-dimensional electron gases (2DEGs). The requirement for surface cleanliness is also less stringent due to the higher penetration depth of soft X-rays. Additionally, this energy range facilitates resonant ARPES experiments, which provide elemental sensitivity by tuning the photon energy to specific absorption edges.

Scientific Scope 3： Advancing micro- and nano-devices requires the ability to control electronic states across multiple degrees of freedom. Our experimental system is designed for this purpose, combining several key techniques: spin-resolved analysis via a VLEED detector, in situ electrical gating to probe functional electronic structure in device-relevant conditions, and the application of uniaxial strain to induce and study novel quantum phases.

Related beamlines:

SX-ARPES beamlines:

http://e-ssrf.sari.ac.cn/beamlines_2024/sr_72267/beamline_maps/bl09u/xzjs/

https://photon-science.desy.de/facilities/petra_iii/beamlines/p04_xuv_beamline/index_eng.html

Nano-ARPES beamlines:

https://sites.google.com/a/lbl.gov/maestro/maestro-home

https://www.diamond.ac.uk/Instruments/Structures-and-Surfaces/I05.html

http://e-ssrf.sari.ac.cn/beamlines_2024/sr_72267/beamline_maps/bl07u/xzjs/

https://www.synchrotron-soleil.fr/en/beamlines/cassiopee