EuO epitaxy by oxygen scavenging on SrTiO 3 (001): Effect of SrTiO 3 thickness and temperature

Wei Guo, Agham B. Posadas, Sirong Lu, David Smith, Alexander A. Demkov

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

The EuO/SrTiO 3 heterojunction is a promising combination of a ferromagnetic material and a two-dimensional electron system. We explore the deposition of Eu metal on SrTiO 3 /Si pseudo-substrates, with varying SrTiO 3 (STO) thickness, under ultrahigh vacuum conditions. By varying the thickness of the STO layer (2-10 nm) and the deposition temperature (20-300 °C), we investigate the process by which oxygen is scavenged from STO by Eu. In situ x-ray photoelectron spectroscopy is used to investigate the electronic structure of the nominal Eu/STO/Si stack. We find that as a result of Eu deposition, epitaxial EuO is formed on thick STO (6-10 nm), leaving behind a highly oxygen-deficient SrTiO 3-δ layer of ∼4 nm in thickness. However, if the thickness of the STO layer is comparable to or less than the scavenging depth, the crystal structure of STO is disrupted and a solid state reaction between Eu, Si, and STO occurs when the deposition is done at a high temperature (300 °C). On the other hand, at a low temperature (20 °C), only a 1-2 nm-thick EuO interlayer is grown, on top of which the Eu metal appears to be stable. This study elucidates the growth process under different conditions and provides a better understanding and control of this system.

Original languageEnglish (US)
Article number235301
JournalJournal of Applied Physics
Volume124
Issue number23
DOIs
StatePublished - Dec 21 2018

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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