Soft X-Ray ARPES: From Bulk Materials to Buried Heterostructures and Impurities
- Feb 27, 2020
- 2:00 PM - 3:30 PM
- Dr. Vladimir N. Strocov
- Paul Scherrer Institute, PSI Villigen, Switzerland
- Main Topic
- Other Topics
- Prof. Dr. Claudia Felser
- Soft X-Ray ARPES: From Bulk Materials to Buried Heterostructures and Impurities
Vladimir N. Strocov
Swiss Light Source, Paul Scherrer Institute, Villigen-PSI, Switzerland (email@example.com)
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 .
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 , 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 . 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 . 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 . Other cases include magnetic V impurities in topological Bi3Se2 competing with the quantum anomalous Hall effect , 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.
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Last modified: Feb 28, 2020, 12:08:45 AM
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