Proximity-induced ferromagnetism and chemical reactivity in few-layer VSe2 heterostructures

Abstract

Among Transition-Metal Dichalcogenides, mono and few-layers thick VSe2 has gained much recent attention following claims of intrinsic room-temperature ferromagnetism in this system, which have nonetheless proved controversial. Here, we address the magnetic and chemical properties of Fe/VSe2 heterostructure by combining element sensitive absorption spectroscopy and photoemission spectroscopy. Our x-ray magnetic circular dichroism results confirm recent findings that both native mono/few-layer and bulk VSe2 do not show any signature of an intrinsic ferromagnetic ordering. Nonetheless, we find that ferromagnetism can be induced, even at room temperature, after coupling with a Fe thin film layer, with antiparallel alignment of the moment on the V with respect to Fe. We further consider the chemical reactivity at the Fe/VSe2 interface and its relation with interfacial magnetic coupling.

van der Waals Magnets: Material Family, Detection and Modulation of Magnetism, and Perspective in Spintronics

“…This opinion is confirmed by the long‐range magnetic order in monolayer VSe 2 induced by interfacial hybridization [ 105 ] or magnetic proximity effects (MPE). [ 106 ] As illustrated in Figure 4f,g, the V loop shows hysteric characteristics in the element‐specific XMCD measurements on VSe 2 /Co and VSe 2 /Fe heterostructures, which is a clear proof for the ferromagnetism in VSe 2 . Beyond that, the presence of spin frustration [ 107 ] in monolayer VSe 2 is another evidence for the unstable magnetic state, which possibly arises from the triangular spin structure where the mutual anti‐alignment of spin cannot be realized (Figure 4h).…”

“…g) The elemental‐resolved XMCD signal of Fe (red) and V (green) as a function of magnetic field measured on the MBE‐grown monolayer VSe 2 capped by a Fe layer measured at 300 K. Reproduced with permission. [ 106 ] Copyright 2019, American Physical Society. h) Schematic diagram of spin frustration in VSe 2 .…”

“…[105] Furthermore, one can obtain elementresolvable measurement results and analyze the spin and orbital momentum of magnetic atoms through XMCD. [106] However, the demand for synchrotron radiation source may constrain its practical applications. Recently, XMCD has been applied www.advancedsciencenews.com www.advancedscience.com to explore the interfacial-hybridization-induced and proximityinduced magnetism in monolayer VSe 2 via the element-specific measurements (Figure 4f,g).…”

“…Recently, XMCD has been applied www.advancedsciencenews.com www.advancedscience.com to explore the interfacial-hybridization-induced and proximityinduced magnetism in monolayer VSe 2 via the element-specific measurements (Figure 4f,g). [105,106]…”

Two‐dimensional magnetic transition metal chalcogenides

“…The ferromagnetism in ML VSe 2 can be promoted, even at room temperature, after coupling with ferromagnetic Co or Fe thin films 51,52 . Figure 2A shows a contamination‐free Co/VSe 2 interface prepared by in situ thermally deposition of Co onto ML VSe 2 on graphite under ultrahigh vacuum 51 .…”