Berlin 2012 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 22: Correlated Electrons: Low-dimensional Systems - Materials 1

TT 22.6: Vortrag

Mittwoch, 28. März 2012, 10:45–11:00, H 0104

Soft-X-Ray ARPES: From Three-Dimensional Materials to Multilayer Heterostructures — •Vladimir N. Strocov¹, Masaki Kobayashi^1,2, Ming Shi¹, Thorsten Schmitt¹, and Luc Patthey¹ — ¹Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland — ²Department of Applied Chemistry, University of Tokyo, Tokyo 113-8656, Japan

Soft-X-ray ARPES benefits from free-electron final states, simplified matrix elements and increasing photoelectron escape depth. The latter, apart from allowing bulk sensitivity and access to deep layers in heterostructures, improves intrinsic resolution in surface-perpendicular momentum k_z crucial for three-dimensional (3D) systems.

The ADRESS beamline (J. Synchrotron Rad. 17 (2010) 631) delivers soft X-rays with photon energies from hv = 300 to 1600 eV. The flux tops up 10¹³ photons/s/0.01%BW which allows breakthrough of the notorious valence band cross-section problem. The acquisition time is typically only a few minutes with energy resolution of 110 meV, increasing to a few tens of with 60 meV.

Apart from technical details, we give an overview of recent soft-X-ray ARPES results, including 3D Fermi surface (FS) of VSe₂, with its warping giving rise to 3D charge density waves, alternating FS shapes in 3D pnictides, topological surface state in 3D valence band of PbBi₄Te₇, FS of buried layers in LaAlO₃/LaNiO₃ and LaAlO₃/SrTiO₃ hererostructures, etc. These results demonstrate an immense potential of soft-X-ray ARPES for electronic structure of 3D materials and multilayer heterostructures.