Room-temperature intrinsic ferromagnetism in epitaxial CrTe2 ultrathin films

Zhang, Xiaoqian; Lu, Qiangsheng; Liu, Wenqing; Niu, Wei; Sun, Jiabao; Cook, Jacob; Vaninger, Mitchel; Miceli, P. F.; Singh, David J.; Lian, Shang Wei; Chang, Tay Rong; He, Xiaoqing; Du, Jun; He, Liang; Zhang, Rong; Bian, Guang; Xu, Yongbing

doi:10.1038/s41467-021-22777-x

Cited by 231 publications

(218 citation statements)

References 101 publications

(145 reference statements)

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“…By building heterostructures using PMA materials with Curie temperature above 300 K, such as few-layer CrTe2 (Ref. 51 ), room-temperature PM switching through OTT can be achieved, promising for realistic applications.…”

Section: Discussionmentioning

confidence: 99%

Orbit-Transfer Torque Driven Field-Free Switching of Perpendicular Magnetization

Zhu

et al. 2022

Chinese Phys. Lett.

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The reversal of perpendicular magnetization (PM) by electric control is crucial for high-density integration of low-power magnetic random-access memory. Although the spin-transfer torque and spin-orbit torque technologies have been used to switch the magnetization of a free layer with perpendicular magnetic anisotropy, the former has limited endurance because of the high current density directly through the junction, while the latter requires an external magnetic field or unconventional configuration to break the symmetry. Here we propose and realize the orbit-transfer torque (OTT), that is, exerting torque on the magnetization using the orbital magnetic moments, and thus demonstrate a new strategy for current-driven PM reversal without external magnetic field. The perpendicular polarization of orbital magnetic moments is generated by a direct current in a few-layer WTe2 due to the existence of nonzero Berry curvature dipole, and the polarization direction can be switched by changing the current polarity. Guided by this principle, we construct the WTe2/Fe3GeTe2 heterostructures to achieve the OTT driven field-free deterministic switching of PM.

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Section: Discussionmentioning

confidence: 99%

Orbit-Transfer Torque Driven Field-Free Switching of Perpendicular Magnetization

Zhu

et al. 2022

Chinese Phys. Lett.

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“…For few-layer films, CrTe 2 exhibits intrinsic ferromagnetism with a Curie temperature up to 300 K, an atomic magnetic moment of ~0.21 µB/Cr, and a perpendicular magnetic anisotropy (PMA) constant (Ku) of 4.89 × 10 5 erg/cm 3 at room temperature, which was unambiguously evidenced by a superconducting quantum interference device and X-ray magnetic circular dichroism. Even in a monolayer sample, ferromagnetic order still exists with T C ~200 K [60].…”

Section: Ferromagnetic 2d Vdw Materialsmentioning

confidence: 99%

“…MBE is another efficient way to synthesize ultrathin films, and exhibits great superiority with respect to controlling the thickness of the materials. In previous reports, some 2D materials, such as CrBr 3 (Figure 8g) [77], CrTe 2 [60], MnSe 2 [80], and MnSn [94], were successfully synthesized via MBE. However, the costly facilities and complex processes hinder its development in the growth of 2D materials.…”

Section: Mnbi 2n Te 3n+1mentioning

confidence: 99%

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Atomically Thin 2D van der Waals Magnetic Materials: Fabrications, Structure, Magnetic Properties and Applications

Kong

Zhao

et al. 2022

Coatings

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Two-dimensional (2D) van der Waals (vdW) magnetic materials are considered to be ideal candidates for the fabrication of spintronic devices because of their low dimensionality, allowing the quantization of electronic states and more degrees of freedom for device modulation. With the discovery of few-layer Cr2Ge2Te6 and monolayer CrI3 ferromagnets, the magnetism of 2D vdW materials is becoming a research focus in the fields of material science and physics. In theory, taking the Heisenberg model with finite-range exchange interactions as an example, low dimensionality and ferromagnetism are in competition. In other words, it is difficult for 2D materials to maintain their magnetism. However, the introduction of anisotropy in 2D magnetic materials enables the realization of long-range ferromagnetic order in atomically layered materials, which may offer new effective means for the design of 2D ferromagnets with high Curie temperature. Herein, current advances in the field of 2D vdW magnetic crystals, as well as intrinsic and induced ferromagnetism or antiferromagnetism, physical properties, device fabrication, and potential applications, are briefly summarized and discussed.

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“…Two dimensional (2D) heterostructures obtained by stacking van der Waals (vdW) layers have attracted intense interest for fundamental research and applications in electronics [1] , optoelectronics [2] , spintronics [3] , and valleytronics [4] . In particular, moiré superlattices achieved by aligning or twisting individual 2D layers offer an additional degree of freedom for manipulating the electronic structure.…”

Section: Introductionmentioning

confidence: 99%

Dative Epitaxy of Commensurate Monocrystalline Covalent van der Waals Moiré Supercrystal

et al. 2022

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Realizing van der Waals (vdW) epitaxy in the 80's represents a breakthrough that circumvents the stringent lattice matching and processing compatibility requirements in conventional covalent heteroepitaxy. However, due to the weak vdW interactions, there is little control over film qualities by the substrate. Typically, discrete domains with a spread of misorientation angles are formed, limiting the applicability of vdW epitaxy. Here we report the epitaxial growth of monocrystalline, covalent Cr5Te8 2D crystals on monolayer vdW WSe2 by chemical vapor deposition, driven by interfacial dative bond formation. The lattice of Cr5Te8, with a lateral dimension of a few ten microns, is fully commensurate with that of WSe2 via 3 × 3 (Cr5Te8)/7 × 7 (WSe2) supercell matching, forming a single-crystalline moiré superlattice. Our work has established a conceptually distinct paradigm of thin film epitaxy termed "dative epitaxy", which takes full advantage of covalent epitaxy with chemical bonding for fixing the atomic registry and crystal orientation, while circumventing its stringent lattice matching and processing compatibility requirements; conversely, it ensures the full flexibility of vdW epitaxy, while avoiding its poor orientation control. Cr5Te8 2D crystals grown by dative epitaxy exhibit square magnetic hysteresis, suggesting minimized interfacial defects that can serve as pinning sites.

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Room-temperature intrinsic ferromagnetism in epitaxial CrTe2 ultrathin films

Cited by 231 publications

References 101 publications

Orbit-Transfer Torque Driven Field-Free Switching of Perpendicular Magnetization

Orbit-Transfer Torque Driven Field-Free Switching of Perpendicular Magnetization

Atomically Thin 2D van der Waals Magnetic Materials: Fabrications, Structure, Magnetic Properties and Applications

Dative Epitaxy of Commensurate Monocrystalline Covalent van der Waals Moiré Supercrystal

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