A-branch – ARPES

The A-branch endstation consists of several UHV chambers, coupled by a central radial distribution chamber. This layout permits working in parallel on each chamber, independently of all others.

For details of the measurement chamber, the two preparation chambers and the scanning tunnelling microscope, see the dedicated pages. The other components of the endstation are:

Loadlock

The loadlock has a 6-slot carousel. Preliminary outgassing is possible by either direct current heating through the sample or resistive heating by a filament underneath the receiver. At present only one sample can be heated at a time. It takes about 2 hours to attain a satisfactory pressure to move the sample into the main chambers.

Vacuum suitcase

It is possible to dock vacuum suitcases to the endstation. Please discuss the details of your suitcase with the beamline staff to ensure compatibility.

Storage chamber

There is a 12-slot carousel for short-term UHV storage of samples

Transfer chamber

The central transfer chamber (P=9×10⁻¹¹mbar) has a distribution arm with two thermally isolated slots. The receiver can be LN2 cooled to enable cold (<100K) transfers between chambers.

Free ports

There is one free DN63CF port on the transfer chamber which could in principle accommodate a small custom chamber. Discuss with the beamline staff, many months in advance, if you are interested in using this.

B-branch (spinARPES)

The B-branch is currently in the installation and commissioning phase. It is already open for expert commissioning proposals, will become available for general users for the spring 2023 cycle (March–August).

The beamline optics for the B-branch of Bloch are essentially identical to those of the A-branch, but here the experimental endstation offers spin-resolved ARPES.

The analysis chamber is equipped with a PHOIBOS 150 hemispherical analyzer from Specs, with a combined 2D-CCD for regular ARPES and 3D-VLEED for spin resolution. This analyzer is capable of electronic deflection to simulate polar or tilt rotations without moving the sample. The expected energy resolution with the CCD detector is <5meV, with angular resolution <0.1°.

Measurement of all three spin vector components is accomplished with a single Ferrum VLEED detector combined with a magnetic spin-rotator lens.

Currently, the analysis chamber uses a 4-axis closed-cycle cryomanipulator, with an expected sample temperature range of <20K –> 400K. Work is underway to upgrade this to a 6-axis manipulator, although the timeline is not currently known.

Sample preparation by cleaving, sputtering, heating or evaporation is possible.