Highly‐Tunable Intrinsic Room‐Temperature Ferromagnetism in 2D van der Waals Semiconductor Cr_xGa_1−xTe

Abstract

The combination of semiconductivity and tunable ferromagnetism is pivotal for electrical control of ferromagnetism and next-generation low-power spintronic devices. However, Curie temperatures (T C ) for most traditional intrinsic ferromagnetic semiconductors (≤200 K) and recently discovered two-dimensional (2D) ones (<70 K) are far below room temperature. 2D van der Waals (vdW) semiconductors with intrinsic room-temperature ferromagnetism remain elusive considering the unfavored 2D long-range ferromagnetic order indicated by Mermin-Wagner theorem. Here, vdW semiconductor Cr x Ga 1−x Te crystals exhibiting highly tunable above-room-temperature ferromagnetism with bandgap 1.62-1.66 eV are reported. The saturation magnetic moment (M sat ) of Cr x Ga 1−x Te crystals can be effectively regulated up to ≈5.4 times by tuning Cr content and ≈75.9 times by changing the thickness. vdW Cr x Ga 1−x Te ultrathin semiconductor crystals show robust room-temperature ferromagnetism with the 2D quantum confinement effect, enabling T C 314.9-329 K for nanosheets, record-high for intrinsic vdW 2D ferromagnetic semiconductors. This work opens an avenue to room-temperature 2D vdW ferromagnetic semiconductor for 2D electronic and spintronic devices.

Highly-tunable ferromagnetism in Cr-doped layered van der Waals NiTe2 crystals with high air stability

“…34 This is also consistent with many previous reports on the introduction of ferromagnetism by Cr doping. 20,21 Corresponding to our previous XRD tests, the lower Curie temperature of 2# than that of 1# is attributed to the presence of more Cr content in a higher valence state.…”

“…14–18 The introduction of ferromagnetism in vdW crystals can also be achieved by the doping of magnetic elements such as Fe 1/3 TaS 2 , CrWoTe 2 , CrGaTe, and CrMoTe 2 . 19–22…”

Two-dimensional magnetic atomic crystals

“…In our laboratory, Ferromagnetic van der Waals crystals near room temperature were obtained by Cr doping in WTe 2 , 158 2H-MoTe 2 , 159 VTe 2 160 and GaTe. 161 It is an effective route to regulate the Curie temperature of 2D ferromagnetic crystals through ionic gates. The original Curie temperature of a monolayer Fe 3 GeTe 2 was 205 K, but an ionic gate can raise its T C to over room temperature (Fig.…”

Controllable CVD Growth of 2D Cr5Te8 Nanosheets with Thickness-Dependent Magnetic Domains

“…As a crucial component of the 2D material family, due to the promising application prospect in spintronics and magnetic memory devices, , 2D magnetic materials with exceptional electrical , and photoelectrical , properties as well as novel magnetic − properties have received extensive attention. Particularly, it is found that monolayer Fe 3 GeTe 2 still retained ferromagnetic long-range order at low temperatures. − Thus far, ultrathin Cr x Ga 1– x Te nanosheets have exhibited intrinsic room-temperature ferromagnetism, which renders them ideal candidates for carrier control . Despite 2D magnetic materials hold promising prospects for exploration and practical applications, its magnetic behavior especially in the magnetic domain structure is still in its nascent stages.…”

“…10−12 Thus far, ultrathin Cr x Ga 1−x Te nanosheets have exhibited intrinsic room-temperature ferromagnetism, which renders them ideal candidates for carrier control. 13 Despite 2D magnetic materials hold promising prospects for exploration and practical applications, its magnetic behavior especially in the magnetic domain structure is still in its nascent stages. Consequently, it is essential to explore the controllable growth and the magnetic domain structure of 2D magnetic materials.…”