Above-room-temperature ferromagnetism in ultrathin van der Waals magnet

Abstract

Two-dimensional (2D) magnetic van der Waals materials provide a powerful platform for studying fundamental physics of low-dimensional magnetism, engineering novel magnetic phases, and enabling ultrathin and highly tunable spintronic devices. To realize high quality and practical devices for such applications, there is a critical need for robust 2D magnets with ordering temperatures above room temperature that can be created via exfoliation. Here the study of exfoliated flakes of cobalt substituted Fe5GeTe2 (CFGT) exhibiting magnetism above room temperature is reported. Via quantum magnetic imaging with nitrogen-vacancy centers in diamond, ferromagnetism at room temperature was observed in CFGT flakes as thin as 16 nm. This corresponds to one of the thinnest room-temperature 2D magnet flakes exfoliated from robust single crystals, reaching a thickness relevant to practical spintronic applications. The Curie temperature Tc of CFGT ranges from 310 K in the thinnest flake studied to 328 K in the bulk. To investigate the prospect of high-temperature monolayer ferromagnetism, Monte Carlo calculations were performed which predicted a high value of Tc ~270 K in CFGT monolayers. Pathways towards further enhancing monolayer Tc are discussed. These results support CFGT as a promising platform to realize high-quality room-temperature 2D magnet devices.

References in corpus (8)

• Magnetic 2D materials and heterostructures
• Probing magnetism in 2D materials at the nanoscale with single spin microscopy
• Highly efficient spin-orbit torque and switching of layered ferromagnet Fe3GeTe2
• Tuning Magnetic Order in the van der Waals Metal Fe5GeTe2 by Cobalt Substitution
• Magnetic imaging with spin defects in hexagonal boron nitride
• Characterization of room-temperature in-plane magnetization in thin flakes of CrTe${}_2$ with a single spin magnetometer
• Observation of Superconductivity Induced Ferromagnetism in an Fe-Chalcogenide Superconductor
• Antiferromagnetic order in Co-doped Fe${}_5$GeTe${}_2$ probed by resonant magnetic x-ray scattering

Cited by in corpus (8)

• Deterministic and non-volatile switching of all-van der Waals spin-orbit torque system above room temperature without external magnetic fields
• Progress and Prospects in Two-Dimensional Magnetism of van der Waals Materials
• Nitrogen-vacancy magnetometry of CrSBr by diamond membrane transfer
• Flat bands and magnetism in $\mathbf{F}{\mathbf{e}}_4\mathbf{GeT}{\mathbf{e}}_2$ and $\mathbf{F}{\mathbf{e}}_5\mathbf{GeT}{\mathbf{e}}_2$ due to bipartite crystal lattices
• Tuning magnetic anisotropy in Fe${}_5$GeTe${}_2$ monolayer through doping and strain
• Nearly-room-temperature ferromagnetism and tunable anomalous Hall effect in atomically thin Fe4CoGeTe2
• Magnetic excitations and absence of charge order in the van der Waals ferromagnet Fe${}_{4.75}$GeTe${}_2$
• Quantum Imaging of Ferromagnetic van der Waals Magnetic Domain Structures at Ambient Conditions