TY - JOUR
T1 - EuO epitaxy by oxygen scavenging on SrTiO 3 (001)
T2 - Effect of SrTiO 3 thickness and temperature
AU - Guo, Wei
AU - Posadas, Agham B.
AU - Lu, Sirong
AU - Smith, David J.
AU - Demkov, Alexander A.
N1 - Funding Information:
This research was partially supported by the National Science Foundation (NSF) through the Center for Dynamics and Control of Materials: an NSF MRSEC under Cooperative Agreement No. DMR-1720595 and by the Air Force Office of Scientific Research (AFOSR) under Grant No. FA9550-18-1-0053. All calculations were performed at the Texas Advanced Computing Center (TACC).
Publisher Copyright:
© 2018 Author(s).
PY - 2018/12/21
Y1 - 2018/12/21
N2 - 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.
AB - 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.
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U2 - 10.1063/1.5059560
DO - 10.1063/1.5059560
M3 - Article
AN - SCOPUS:85058801121
VL - 124
JO - Journal of Applied Physics
JF - Journal of Applied Physics
SN - 0021-8979
IS - 23
M1 - 235301
ER -