Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit
Bevin Huang,Genevieve Clark,Efrén Navarro-Moratalla,Dahlia R. Klein,Ran Cheng,Kyle L. Seyler,Ding Zhong,E. R. Schmidgall,Michael A. McGuire,David Cobden,Wang Yao,Di Xiao,Pablo Jarillo-Herrero,Xiaodong Xu +13 more
TLDR
Xu et al. as mentioned in this paper used magneto-optical Kerr effect microscopy to show that monolayer chromium triiodide (CrI3) is an Ising ferromagnet with out-of-plane spin orientation.Abstract:
Magneto-optical Kerr effect microscopy is used to show that monolayer chromium triiodide is an Ising ferromagnet with out-of-plane spin orientation. The question of what happens to the properties of a material when it is thinned down to atomic-scale thickness has for a long time been a largely hypothetical one. In the past decade, new experimental methods have made it possible to isolate and measure a range of two-dimensional structures, enabling many theoretical predictions to be tested. But it has been a particular challenge to observe intrinsic magnetic effects, which could shed light on the longstanding fundamental question of whether intrinsic long-range magnetic order can robustly exist in two dimensions. In this issue of Nature, two groups address this challenge and report ferromagnetism in atomically thin crystals. Xiang Zhang and colleagues measured atomic layers of Cr2Ge2Te6 and observed ferromagnetic ordering with a transition temperature that, unusually, can be controlled using small magnetic fields. Xiaodong Xu and colleagues measured atomic layers of CrI3 and observed ferromagnetic ordering that, remarkably, was suppressed in double layers of CrI3, but restored in triple layers. The two studies demonstrate a platform with which to test fundamental properties of purely two-dimensional magnets. Since the discovery of graphene1, the family of two-dimensional materials has grown, displaying a broad range of electronic properties. Recent additions include semiconductors with spin–valley coupling2, Ising superconductors3,4,5 that can be tuned into a quantum metal6, possible Mott insulators with tunable charge-density waves7, and topological semimetals with edge transport8,9. However, no two-dimensional crystal with intrinsic magnetism has yet been discovered10,11,12,13,14; such a crystal would be useful in many technologies from sensing to data storage15. Theoretically, magnetic order is prohibited in the two-dimensional isotropic Heisenberg model at finite temperatures by the Mermin–Wagner theorem16. Magnetic anisotropy removes this restriction, however, and enables, for instance, the occurrence of two-dimensional Ising ferromagnetism. Here we use magneto-optical Kerr effect microscopy to demonstrate that monolayer chromium triiodide (CrI3) is an Ising ferromagnet with out-of-plane spin orientation. Its Curie temperature of 45 kelvin is only slightly lower than that of the bulk crystal, 61 kelvin, which is consistent with a weak interlayer coupling. Moreover, our studies suggest a layer-dependent magnetic phase, highlighting thickness-dependent physical properties typical of van der Waals crystals17,18,19. Remarkably, bilayer CrI3 displays suppressed magnetization with a metamagnetic effect20, whereas in trilayer CrI3 the interlayer ferromagnetism observed in the bulk crystal is restored. This work creates opportunities for studying magnetism by harnessing the unusual features of atomically thin materials, such as electrical control for realizing magnetoelectronics12, and van der Waals engineering to produce interface phenomena15.read more
Citations
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Gate-tunable room-temperature ferromagnetism in two-dimensional Fe 3 GeTe 2 .
Yujun Deng,Yujun Deng,Yijun Yu,Yijun Yu,Yichen Song,Yichen Song,Jingzhao Zhang,Naizhou Wang,Naizhou Wang,Zeyuan Sun,Zeyuan Sun,Yangfan Yi,Yangfan Yi,Yizheng Wu,Yizheng Wu,Shiwei Wu,Shiwei Wu,Junyi Zhu,Jing Wang,Jing Wang,Xianhui Chen,Xianhui Chen,Yuanbo Zhang,Yuanbo Zhang +23 more
TL;DR: It is found that the itinerant ferromagnetism persists in Fe3GeTe2 down to the monolayer with an out-of-plane magnetocrystalline anisotropy, which opens up opportunities for potential voltage-controlled magnetoelectronics based on atomically thin van der Waals crystals.
Journal ArticleDOI
Two-dimensional materials from high-throughput computational exfoliation of experimentally known compounds
Nicolas Mounet,Marco Gibertini,Philippe Schwaller,Davide Campi,Andrius Merkys,Andrius Merkys,Antimo Marrazzo,Thibault Sohier,Ivano E. Castelli,Andrea Cepellotti,Giovanni Pizzi,Nicola Marzari +11 more
TL;DR: The largest available database of potentially exfoliable 2D materials has been obtained via high-throughput calculations using van der Waals density functional theory.
Journal ArticleDOI
Strong room-temperature ferromagnetism in VSe2 monolayers on van der Waals substrates.
Manuel Bonilla,Sadhu Kolekar,Yujing Ma,Horacio Coy Diaz,Vijaysankar Kalappattil,Raja Das,Tatiana Eggers,Humberto R. Gutierrez,Manh-Huong Phan,Matthias Batzill +9 more
TL;DR: Reducing the dimensionality of paramagnetic V Se2 results in the emergence of ferromagnetism that is observed in a monolayer and up to room temperature, making VSe2 an attractive material for van der Waals spintronics applications.
Journal ArticleDOI
Two-dimensional magnetic crystals and emergent heterostructure devices
TL;DR: Recognizing that magnetic anisotropy can be used to induce stable magnetism in atomic monolayers, Gong and Zhang provide an overview of the materials available and the physical understanding of the effects and then discuss how these effects could be exploited for widespread practical applications.
Journal ArticleDOI
Magnetism in two-dimensional van der Waals materials.
TL;DR: These cleavable materials provide the ideal platform for exploring magnetism in the two-dimensional limit, where new physical phenomena are expected, and represent a substantial shift in the authors' ability to control and investigate nanoscale phases.
References
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Electric Field Effect in Atomically Thin Carbon Films
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Atomically thin MoS2: a new direct-gap semiconductor
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Journal Article
Experimental Observation of Quantum Hall Effect and Berry's Phase in Graphene
TL;DR: An experimental investigation of magneto-transport in a high-mobility single layer of graphene observes an unusual half-integer quantum Hall effect for both electron and hole carriers in graphene.
Journal ArticleDOI
Emerging Photoluminescence in Monolayer MoS2
Andrea Splendiani,Liang Sun,Yuanbo Zhang,Tianshu Li,Jonghwan Kim,Chi-Yung Chim,Giulia Galli,Feng Wang,Feng Wang +8 more
TL;DR: This observation shows that quantum confinement in layered d-electron materials like MoS(2), a prototypical metal dichalcogenide, provides new opportunities for engineering the electronic structure of matter at the nanoscale.
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