Extraction of phase information approximating the demagnetization field within a thin-foiled magnet using electron holography observation

Sujin Lee; Atsuko Sato; Takehiro Tamaoka; Kunio Yubuta; Mitsunari Auchi; Taisuke Sasaki; Tadakatsu Ohkubo; Kazuhiro Hono; Yasukazu Murakami

doi:10.1093/jmicro/dfac066

Extraction of phase information approximating the demagnetization field within a thin-foiled magnet using electron holography observation

Microscopy (Oxf). 2023 Aug 4;72(4):343-352. doi: 10.1093/jmicro/dfac066.

Authors

Sujin Lee¹, Atsuko Sato¹, Takehiro Tamaoka², Kunio Yubuta¹, Mitsunari Auchi², Taisuke Sasaki³, Tadakatsu Ohkubo³, Kazuhiro Hono³, Yasukazu Murakami^{1

2}

Affiliations

¹ Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Fukuoka 819-0395, Japan.
² The Ultramicroscopy Research Center, Kyushu University, Fukuoka 819-0395, Japan.
³ National Institute for Materials Science, Tsukuba 305-0047, Japan.

PMID: 36420894
DOI: 10.1093/jmicro/dfac066

Abstract

This paper proposes a method that provides a phase image related to the demagnetization field (Hd) within a thin-foil permanent magnet using electron holography. The observation of Hd remains a significant challenge because electron holography in principle allows only imaging of the magnetic flux density (B), which is a mixture of the contributions from magnetization (M), stray magnetic field (Hs) outside of the specimen and Hd inside of the specimen. The phase map approximating Hd, which was determined by processing of the electron holography observation from a Nd2Fe14B single-crystalline specimen, showed a good agreement with the prediction by micromagnetic theory. With respect to permanent magnets, this method can be applied to examinations about the coercivity mechanism, which is sensitive to the demagnetization field. Graphical Abstract.

Keywords: coercivity; demagnetization; electron holography; electron microscopy; nucleation of reverse magnetic domains; permanent magnet.