Soft X-Ray ARPES: From Bulk Materials to Buried Heterostructures and Impurities

Date

Feb 27, 2020

Time

2:00 PM - 3:30 PM

Speaker

Dr. Vladimir N. Strocov

Affiliation

Paul Scherrer Institute, PSI Villigen, Switzerland

Language

en

Main Topic

Materialien

Other Topics

Materialien

Host

Prof. Dr. Claudia Felser

Description

Soft X-Ray ARPES: From Bulk Materials to Buried Heterostructures and Impurities Vladimir N. Strocov Swiss Light Source, Paul Scherrer Institute, Villigen-PSI, Switzerland (vladimir.strocov@psi.ch) ABSTRACT Soft-X-ray ARPES (SX-ARPES) in the energy range around 1 keV benefits from enhanced photoelectron escape depth, sharp definition of 3D electron momentum k, and resonant photoexcitation delivering chemical specificity. These spectroscopic advantages allow SX-ARPES to push k-resolved electronic-structure investigations from bulk materials to buried heterostructures and impurity systems [1]. Bulk materials. – Applications of SX-ARPES to bulk materials are based on sharp definition of the out-of-plane momentum resulting from the enhanced photoelectron delocalization. Examples include 3D-nested Fermi surface of VSe2 forming exotic charge-density waves [2], 3D effects in complex oxides connected with their polaronic activity, 3D band dispersions in topological materials, etc. Buried heterostructures. – Semiconductor systems are illustrated by AlGaN/GaN high-electron-mobility heterostructures, where SX-ARPES resolves anisotropic Fermi surface (Figure) and band dispersions of the interfacial quantum-well states [3]. A "drosophila" oxide interface is LaAlO3/SrTiO3. Resonant photoexcitation at the Ti L-edge resolves here interfacial subbands, whose peak-dip-hump spectral function identifies a multiphonon polaronic nature of the charge carriers [4]. Further cases include EuO/Si spin injectors, EuS/ Bi3Se2 topological interfaces, etc. Impurity systems. – Ga(Mn)As is a paradigm diluted magnetic semiconductor. Resonant photo-excitation at the Mn L-edge identifies energy alignment and hybridization of the Mn impurities with host GaAs, disclosing the mechanism of ferromagnetic electron transport [5]. Other cases include magnetic V impurities in topological Bi3Se2 competing with the quantum anomalous Hall effect [6], etc. This review on the spectroscopic potential of SX-ARPES is concluded by introducing a multichannel spin detector iMott whose four-order efficiency increase will propel spin-texture analysis from bulk materials to buried heterostructures and impurities. REFERENCES 1. V.N. Strocov et al., J. Synchr. Rad. 236 (2019) 1 2. V.N. Strocov et al., Phys. Rev. Lett. 109 (2012) 086401 3. L.L. Lev et al., Nature Comm. 9 (2018) 2653 4. C. Cancellieri et al., Nature Comm. 7 (2016) 10386 5. M. Kobayashi et al., Phys. Rev. B 89 (2014) 205204 6. J. Krieger et al., Phys. Rev. B 96 (2017) 184402

Links

• MPI CPfS

Last modified: Feb 28, 2020, 12:08:45 AM