Spin Resolved Photoemission (Cx1)

Caption: Drawing of the CASSIOPEE Spin-Resolved Photoemission experiment.

Analyzer and spin detection

The Spin-Resolved Photoemission experiment is equipped with a Scienta SES2002 electron analyzer, which has been modified by the Scienta company to incorporate a Mott detector for spin analysis. Part of the electron beam is sent towards the classical Scienta 2D detector, while the rest goes towards the Mott detector through a transfer optics.
The analyzer is mounted with its slits horizontal. The angular analysis is then performed in the horizontal direction. To integrate the Mott detector, the 2D detector has been reduced to 1”, thus reducing the angular acceptance of the analyzer to around ±8°.

Caption: Schematic view of the Scienta SES 2002 and its transfer optics to the Mott detector.

Inside the Mott detector, the electron beam is scattered by a gold target, and the scattering asymmetry is measured parallel and perpendicular to the sample surface, thus measuring the magnetization components in these two directions.
The Mott detector was built in the University of Edinburgh, by Prof. Murray Campbell.

Caption: The Mott detector, without one of its four channelplates.

Sample holder

The Spin-Resolved Photoemission experiment is equipped with a 5 axis sample holder, with a motorized Z translation, manual X and Y translations, and manual  and rotations. The sample can be cooled down to 40 K thanks to a liquid He cryostat.

Caption: View inside the Spin-Resolved Photoemission experiment, with its sample holder, and the Scienta SES2002 electron analyzer behind.

Magnetic field

The spin resolved measurements are done in the remanent state. The sample can be magnetized by an in-vacuum electromagnet, which can produce a magnetic field up to 1200 Oe.

Caption: Drawing of the Spin Resolved Photoemission experiment electromagnet.

Beam size

The beam is sent to the Spin-Resolved Photoemission experiment by a toroidal mirror which also focuses the beam. The beam size is quite large, not to damage the sample during long acquisitions.

Caption: Beam size in to the Spin-Resolved Photoemission experiment at 9 eV, calculated by ray tracing. The dimensions of the beam are 350 (horizontal) x 720 (vertical) µm2.

Caption: Beam size in to the Spin-Resolved Photoemission experiment at 25 eV, calculated by ray tracing. The dimensions of the beam are 250 (horizontal) x 200 (vertical) µm2.