Towards sub-nanometer real-space observation of spin and orbital magnetism at the Fe/MgO interface.
While the performance of magnetic tunnel junctions based on metal/oxide interfaces is determined by hybridization, charge transfer, and magnetic properties at the interface, there are currently only limited experimental techniques with sufficient spatial resolution to directly observe these effects simultaneously in real-space. In this letter, we demonstrate an experimental method based on Electron Magnetic Circular Dichroism (EMCD) that will allow researchers to simultaneously map magnetic transitions and valency in real-space over interfacial cross-sections with sub-nanometer spatial resolution. We apply this method to an Fe/MgO bilayer system, observing a significant enhancement in the orbital to spin moment ratio that is strongly localized to the interfacial region. Through the use of first-principles calculations, multivariate statistical analysis, and Electron Energy-Loss Spectroscopy (EELS), we explore the extent to which this enhancement can be attributed to emergent magnetism due to structural confinement at the interface. We conclude that this method has the potential to directly visualize spin and orbital moments at buried interfaces in magnetic systems with unprecedented spatial resolution.
Department of Engineering Sciences, Uppsala University, Box 534, 75121 Uppsala, Sweden.
Thomas
T
Thersleff
Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan.
Shunsuke
S
Muto
Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden.|Institute of Molecular Physics Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań, Poland.
Mirosław
M
Werwiński
Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden.
Jakob
J
Spiegelberg
Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden.
Yaroslav
Y
Kvashnin
Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden.
Björgvin
B
Hjӧrvarsson
Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden.
Olle
O
Eriksson
Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden.
Ján
J
Rusz
Department of Engineering Sciences, Uppsala University, Box 534, 75121 Uppsala, Sweden.
Klaus
K
Leifer