Probing local magnetic states in the van der Waals ferromagnet Fe4GeTe2 by a vector-field magnetic force microscope

• Published in: Journal of materials science Vol. 59; no. 15; pp. 6415 - 6424
• Main Authors: Yun, Jinyoung, Lee, Yeonkyu, Kim, Geunyong, Seo, Junho, Kang, Beom Tak, Kim, Jun Sung, Choi, Jae-Hyuk, Haberkorn, Nestor, Kim, Jeehoon
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.04.2024; Springer Nature B.V
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Closed loops; Crystallography and Scattering Methods; domain; Electronic Materials; Elongated structure; Ferromagnetic materials; ferromagnetism; Magnetic domains; Magnetic fields; Magnetic force microscopy; Materials Science; Polymer Sciences; Single crystals; Solid Mechanics; temperature; van der Waals forces
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-024-09583-8

In this study, we systematically investigate the magnetic domain structure of Fe 4 GeTe 2 single crystals, employing a cryogenic vector-field magnetic force microscope to probe its temperature and magnetic field dependencies. The material undergoes a spin-reversal transition at around 110 K, leading to a gradual magnetization reorientation from in-plane to out-of-plane as temperature decreases. Our observations reveal a complex domain structure featuring striped shapes enclosed by wavy closed loops, exhibiting limited sensitivity to temperature variations without an external magnetic field. When subject to an out-of-plane magnetic field, the domain structure transforms into micrometric elongated striped shapes, gradually evolving into a more irregular pattern. Conversely, in in-plane measurements, the system displays an inhomogeneous distribution of micrometric bubble-like domains, progressively interconnecting into striped shapes. These distinctive responses are attributed to the interplay between small uniaxial and shape anisotropies within the material. Our findings contribute to a deeper understanding of the magnetic domain dynamics in van der Waals ferromagnetic materials, laying the groundwork for further investigations and potential applications in electronic devices. Graphical Abstract