Room-temperature intrinsic ferromagnetism in epitaxial CrTe2 ultrathin films

TLDR

Room‑temperature ferromagnetism in two‑dimensional magnets is desirable for spintronics, yet achieving it in a device‑compatible form remains difficult. The study demonstrates that molecular‑beam epitaxy can produce single‑ and few‑layer CrTe₂ films that are ferromagnetic at room temperature, paving the way for large‑scale 2D magnet‑based spintronic devices. CrTe₂ layers were grown on bilayer graphene by MBE, and their structural and magnetic properties were characterized. The films show intrinsic ferromagnetism up to 300 K with a 0.21 μB/Cr moment and strong perpendicular anisotropy (Ku = 4.89 × 10⁵ erg cm⁻³), confirmed by SQUID, XMCD, and ARPES band splitting of ~0.2 eV, and the ferromagnetic order persists down to a monolayer with TC ≈ 200 K due to the strong PMA and weak interlayer coupling.

Abstract

Abstract While the discovery of two-dimensional (2D) magnets opens the door for fundamental physics and next-generation spintronics, it is technically challenging to achieve the room-temperature ferromagnetic (FM) order in a way compatible with potential device applications. Here, we report the growth and properties of single- and few-layer CrTe 2 , a van der Waals (vdW) material, on bilayer graphene by molecular beam epitaxy (MBE). Intrinsic ferromagnetism with a Curie temperature ( T C ) up to 300 K, an atomic magnetic moment of ~0.21 $${\mu }_{{\rm{B}}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow> <mml:mi>μ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>B</mml:mi> </mml:mrow> </mml:msub> </mml:math> /Cr and perpendicular magnetic anisotropy (PMA) constant ( K u ) of 4.89 × 10 5 erg/cm 3 at room temperature in these few-monolayer films have been unambiguously evidenced by superconducting quantum interference device and X-ray magnetic circular dichroism. This intrinsic ferromagnetism has also been identified by the splitting of majority and minority band dispersions with ~0.2 eV at Г point using angle-resolved photoemission spectroscopy. The FM order is preserved with the film thickness down to a monolayer ( T C ~ 200 K), benefiting from the strong PMA and weak interlayer coupling. The successful MBE growth of 2D FM CrTe 2 films with room-temperature ferromagnetism opens a new avenue for developing large-scale 2D magnet-based spintronics devices.