Room-temperature in-plane ferromagnetism in Co-substituted Fe 5 GeTe 2 investigated by magnetic x-ray spectroscopy and microscopy

Heppell, Emily; Fujita, Ryuji; Gurung, Gautam; Lin, Jheng-Cyuan; May, Andrew F.; Foerster, Michael; Waqas Khaliq, M.; Angel Niño, Miguel; Valvidares, Manuel; Herrero-Martín, Javier; Gargiani, Pierluigi; Watanabe, Kenji; Taniguchi, Takashi; Backes, Dirk; van der Laan, Gerrit; Hesjedal, Thorsten

doi:10.1088/2053-1583/ada040

Room-temperature in-plane ferromagnetism in Co-substituted Fe ₅ GeTe ₂ investigated by magnetic x-ray spectroscopy and microscopy

Journal Article · Sun Jan 05 23:00:00 EST 2025 · 2D Materials

DOI:https://doi.org/10.1088/2053-1583/ada040· OSTI ID:2496779

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Abstract

The exploration of two-dimensional (2D) van der Waals ferromagnets has revealed intriguing magnetic properties with significant potential for spintronics applications. In this study, we examine the magnetic properties of Co-doped Fe ₅ GeTe ₂ using x-ray photoemission electron microscopy (XPEEM) and x-ray magnetic circular dichroism (XMCD), complemented by density functional theory calculations. Our XPEEM measurements reveal that the Curie temperature ( $T_{C}$ ) of a bilayer of (Co _x Fe $_{1 - x}$ ) $_{5 - δ}$ GeTe ₂ (with x = 0.28) reaches ∼300 K—a notable enhancement over most 2D ferromagnets in the ultrathin limit. Interestingly, the $T_{C}$ shows only a small dependence on film thickness (bulk $T_{C} \approx 340$ K), in line with the observed in-plane (IP) magnetic anisotropy and robust IP exchange coupling. XMCD measurements indicate that the spin moments for both Fe and Co are significantly reduced compared to the theoretical values. These insights highlight the potential of Co-doped Fe ₅ GeTe ₂ for stable, high-temperature ferromagnetic applications in 2D materials.

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Sponsoring Organization:: USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI ID:: 2496779

Alternate ID(s):: OSTI ID: 2482113
OSTI ID: 2586869

Journal Information:: 2D Materials, Journal Name: 2D Materials Journal Issue: 2 Vol. 12; ISSN 2053-1583

Publisher:: IOP PublishingCopyright Statement

Country of Publication:: United Kingdom

Language:: English

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Room-temperature in-plane ferromagnetism in Co-substituted Fe 5 GeTe 2 investigated by magnetic x-ray spectroscopy and microscopy

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Room-temperature in-plane ferromagnetism in Co-substituted Fe ₅ GeTe ₂ investigated by magnetic x-ray spectroscopy and microscopy