Magnetic Field Observation in a Magnetic Tunnel Junction by Scanning Transmission Electron Microscopy

Yuji Kohno; Takehito Seki; Shun Tsuruoka; Shinobu Ohya; Naoya Shibata

doi:10.1093/jmicro/dfad063

Magnetic Field Observation in a Magnetic Tunnel Junction by Scanning Transmission Electron Microscopy

Microscopy (Oxf). 2023 Dec 29:dfad063. doi: 10.1093/jmicro/dfad063. Online ahead of print.

Authors

Yuji Kohno¹, Takehito Seki^{2

3}, Shun Tsuruoka⁴, Shinobu Ohya^{5

4

6}, Naoya Shibata^{2

7}

Affiliations

¹ JEOL Ltd., 3-1-2, Musashino, Akishima, Tokyo 196-8558, Japan.
² Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Yayoi 2-11-16, Bunkyo-ku, Tokyo 113-8656, Japan.
³ PRESTO, Japan Science and Technology Agency, Honcho 4-1-8, Kawaguchi, Saitama 332-0012, Japan.
⁴ Department of Electrical Engineering and Information Systems, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
⁵ Center for Spintronics Research Network (CSRN), School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
⁶ Institute for Nano Quantum Information Electronics (NanoQuine), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
⁷ Nanostructures Research Laboratory, Japan Fine Ceramic Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587, Japan.

PMID: 38155605
DOI: 10.1093/jmicro/dfad063

Abstract

A magnetic tunnel junction (MTJ) consists of two ferromagnetic layers separated by a thin insulating layer. MTJs show tunnel magnetoresistance effect, where the resistance in the direction perpendicular to the insulator layer drastically changes depending on the magnetization directions (parallel or antiparallel) in the ferromagnetic layers. However, direct observation of local magnetizations inside MTJs have been challenging. In this study, we demonstrate direct observation of magnetic flux density distribution inside epitaxially grown Fe/MgO/Fe layers using differential phase contrast scanning transmission electron microscopy. By utilizing newly-developed tilt-scan averaging system for suppressing diffraction contrasts, we clearly visualize parallel and antiparallel states of ferromagnetic layers at nanometer resolution.

Keywords: Dpc Stem; Mram; Mtj; Tdpc; Tilt Scan.

Abstract

Grants and funding