The role of space charge in spin-resolved photoemission experiments
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Author / Producer
Date
2014-04
Publication Type
Journal Article
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yes
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Abstract
Spin-resolved photoemission is one of the most direct ways of measuring the magnetization of a ferromagnet. If all valence band electrons contribute, the measured average spin polarization is proportional to the magnetization. This is even the case if electronic excitations are present, and thus is of particular interest for studying the response of the magnetization to a pump laser pulse. Here, we demonstrate the feasibility of ultrafast spin-resolved photoemission using free electron laser (FEL) radiation and investigate the effect of space charge on the detected spin polarization. The sample is exposed to the radiation of the FEL FLASH in Hamburg. Surprisingly, the measured spin polarization depends on the fluence of the FEL radiation: a higher FEL fluence reduces the measured spin polarization. Space-charge simulations can explain this effect. These findings have consequences for future spin-polarized photoemission experiments using pulsed photon sources.
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published
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Journal / series
Volume
16
Pages / Article No.
43031
Publisher
IOP Publishing
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Edition / version
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Date collected
Date created
Subject
Spin-polarized photoemission; Free electron laser radiation; Space charge
Organisational unit
03986 - Gambardella, Pietro / Gambardella, Pietro
03815 - Vaterlaus, Andreas / Vaterlaus, Andreas