Atomically Thin CrCl<sub>3</sub>: An In-Plane Layered Antiferromagnetic Insulator

Cai, Xinghan; Song, Tiancheng; Wilson, Nathan P.; Clark, Genevieve; He, Minhao; Zhang, Xiaoou; Taniguchi, Takashi; Watanabe, Kenji; Wang, Yao; Xiao, Di; McGuire, Michael A.; Cobden, David; Xu, Xiaodong

doi:10.1021/acs.nanolett.9b01317

Cited by 302 publications

(251 citation statements)

References 45 publications

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“…3e), and that was recently reported for N = 4 in Ref. 45. In odd-N multilayers, instead, dG/dH is predicted to vanish as long as H < H 1 .…”

supporting

confidence: 69%

“…4c, in the even-N multilayers investigated here (N = 2 and 8) and in Ref. 45 (N = 4), H 1 vanishes, due to the negligible in-plane anisotropy (see orange circles in Fig. 4c).…”

supporting

confidence: 56%

“…Consistently with the above considerations, in trilayers theory predicts the conductance to be constant for H < H 1 , and indeed, the measured magnetoconductance curve is rather flat at low field. A small dip is nevertheless present around H = 0 (whose magnitude is sample 44,45 and bias dependent; see Supplementary Fig. 5) that gives rise to the split peak in dG/dH around H = 0 (see the blue curve in Fig.…”

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confidence: 99%

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Determining the phase diagram of atomically thin layered antiferromagnet CrCl3

et al. 2019

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Changes in the spin configuration of atomicallythin, magnetic van-der-Waals multilayers can cause drastic modifications in their optoelectronic properties.Conversely, the optoelectronic response of these systems provides information about the magnetic state, very difficult to obtain otherwise. Here we show that in CrCl 3 multilayers, the dependence of the tunnelling conductance on applied magnetic field (H), temperature (T ), and number of layers (N ) tracks the evolution of the magnetic state, enabling the magnetic phase diagram of these systems to be determined experimentally. Besides a high-field spinflip transition occurring for all thicknesses, the inplane magnetoconductance exhibits an even-odd effect due to a low-field spin-flop transition. If the layer number N is even, the transition occurs at µ 0 H ∼ 0 T due to the very small in-plane magnetic anisotropy, whereas for odd N the net magnetization of the uncompensated layer causes the transition to occur at finite H. Through a quantitative analysis of the phenomena, we determine the interlayer exchange coupling as well as the staggered magnetization, and show that in CrCl 3 shape anisotropy dominates. Our results reveal the rich behaviour of atomically-thin layered antiferromagnets with weak magnetic anisotropy.The recent discovery of magnetism in atomically thin layers exfoliated from bulk van der Waals (vdW) crystals is a major breakthrough 1-13 , with important implications in the field of two-dimensional (2D) materials and heterostructures [14][15][16] . The observation of a giant tunnelling magnetoresistance through CrI 3 multilayers 17-20 , for instance, makes clear that semiconducting vdW antiferromagnets are very interesting systems 21-23 , with potential relevance for technology 24,25 once room-temperature operation is achieved. It is therefore important to identify the microscopic parameters governing the behaviour of these systems, and to understand how they can be determined experimentally. In CrI 3 , the observed phenomenology originates from transitions in which the magnetization of individual layers abruptly flips direction under the application of a perpendicular magnetic field 17-20 (H), as expected when the uniaxial magnetic anisotropy is the dominating energy scale 26,27 . The case of weak anisotropy is different, as a richer variety of magnetic transitions is predicted to occur at lower field 27,28 , and indeed in bulk vdW layered antiferromagnets the occurrence of spin-flop phases 29 is well established 30 . However, the phase diagram of weakly anisotropic atomically-thin vdW layered antiferromagnets, where finite-size effects can give rise to new phenomena 31-34 , has not been determined yet.Here, we investigate atomically thin multilayers of CrCl 3 , a layered vdW antiferromagnetic semiconductor with a small anisotropy that favours spins to lie in the plane of the layers 35-39 ( Fig. 1a; see Supplementary Notes 1-2 and Figures 1-2). We show that the extreme sensitivity of the tunnelling current to the magnetic state can be exploited ...

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“…3e), and that was recently reported for N = 4 in Ref. 45. In odd-N multilayers, instead, dG/dH is predicted to vanish as long as H < H 1 .…”

supporting

confidence: 69%

“…4c, in the even-N multilayers investigated here (N = 2 and 8) and in Ref. 45 (N = 4), H 1 vanishes, due to the negligible in-plane anisotropy (see orange circles in Fig. 4c).…”

supporting

confidence: 56%

mentioning

confidence: 99%

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Determining the phase diagram of atomically thin layered antiferromagnet CrCl3

et al. 2019

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“…Such tiny mismatches are well desirable for experimental explorations. Moreover, bulk CrCl 3 has been successfully exfoliated down to the monolayer limit [60,61], offering the possibility for creating van der Waals heterostructures.…”

Section: Resultsmentioning

confidence: 99%

Valley polarization in monolayer CrX₂ (X = S, Se) with magnetically doping and proximity coupling

Lei

Zhang

et al. 2020

New J. Phys.

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Manipulating the valley degree of freedom as an information carrier has been a focused topic for both fundamental and applied research. Here, using first-principles calculations, we report the identification of monolayer CrX 2 (X=S, Se) as a novel two-dimensional valleytronic crystal. It shows large valley spin splitting in the valence band, attractive for the integration of valleytronics and spintronics. More importantly, through proximity coupling with monolayer CrCl 3 , the valley polarization in monolayer CrX 2 is achieved, which can be further engineered by stacking patterns. Also, the valley polarization in monolayer CrX 2 can be obtained via magnetically doping V and Mn. Specially for V-doped monolayer CrSe 2 , there are no impurity states in the band gap, beneficial for its practical applications. Our works thus provide not only exceptional two-dimensional valleytronic crystals but also promising ways for realizing valley polarizations in them.

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“…[12][13][14][15] Besides CrI3, other layered materials, such as Cr2Ge2Te6, CrCl3, CrBr3, Fe3GeTe2 and FePS3, have been already obtained and verified with long-range magnetic order. [16][17][18][19][20][21] So far, mechanical exfoliation is the major method for preparing 2D magnetic materials.…”

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confidence: 99%

Single-layer CrI3 grown by molecular beam epitaxy

Wang

Zhang

et al. 2020

Science Bulletin

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Single-and few-layer chromium triiodide (CrI3), which has been intensively investigated as a promising platform for two-dimensional magnetism, was usually prepared by mechanical exfoliation. Here, we report on the growth of single-layer CrI3 by molecular beam epitaxy under ultrahigh vacuum. The atomic structures and local density of states have been revealed by scanning tunneling microscopy (STM). Iodine trimers, each of which consists of three I atoms surrounding a three-fold Cr honeycomb center, have been identified as the basic units of the topmost I layer. Different superstructures of single-layer CrI3 with characteristic periodicity around 2-4 nm were obtained on Au(111), but only pristine structure was observed on graphite.At elevated temperatures (423 K), CrI3 was partially decomposed, resulting in the formation of single-layer chromium diiodide. Our bias-dependent STM images suggest that the unoccupied and occupied states are distributed spatial-separately, which is consistent with our density functional theory calculations. The effect of charge distribution on the superexchange interaction in single-layer CrI3 was discussed.Keywords: two-dimensional magnetic materials, CrI3, molecular beam epitaxy, scanning tunneling microscopy 2 / 18 Two-dimensional (2D) magnetic materials, which serve as ideal platforms for investigating spin-related emergent phenomena at reduced dimensions and exhibit potential applications in optoelectronics and spintronics, 1,2 have long been sought. However, as revealed by Mermin-Wagner theorem, long-range magnetic order in 2D systems with isotropic local magnetic interactions are thermodynamically instable at finite temperatures owing to enhanced thermal fluctuations. 3 By introducing magnetic anisotropy, on the other hand, 2D magnetism may exist in a number of layered van der Waals (vdW) materials, for example, transition metal chacogenides and halides. 4-6 Among them, single-and bi-layer chromium triiodide (CrI3) has been recently confirmed with intralayer ferromagnetism (FM) and interlayer antiferromagnetism (AFM). 7,8 The FM coupling in single-layer CrI3, which exhibits a Curie temperature of 45 K, slightly lower than that of the bulk counterpart (61 K), is mainly ascribed to the superexchange interaction between the neighboring Cr atoms mediated by the bridging I atoms. 9 The easy magnetization direction is out of plane with an anisotropy energy about 0.50-0.69 meV/Cr, according to density functional theory (DFT) calculations. 10,11 The magnetic tunneling junction consisting of four-layer CrI3 sandwiched with two graphene layers as the electrodes performs a magnetoresistance change as large as 19,000%, 12 demonstrating the advantages of layered vdW materials for fabricating advanced spintronic devices. [12][13][14][15] Besides CrI3, other layered materials, such as Cr2Ge2Te6, CrCl3, CrBr3, Fe3GeTe2 and FePS3, have been already obtained and verified with long-range magnetic order. [16][17][18][19][20][21] So far, mechanical exfoliation is the major method for preparing 2D magn...

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Atomically Thin CrCl₃: An In-Plane Layered Antiferromagnetic Insulator

Cited by 302 publications

References 45 publications

Determining the phase diagram of atomically thin layered antiferromagnet CrCl3

Determining the phase diagram of atomically thin layered antiferromagnet CrCl3

Valley polarization in monolayer CrX₂ (X = S, Se) with magnetically doping and proximity coupling

Single-layer CrI3 grown by molecular beam epitaxy

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Atomically Thin CrCl3: An In-Plane Layered Antiferromagnetic Insulator

Cited by 302 publications

References 45 publications

Determining the phase diagram of atomically thin layered antiferromagnet CrCl3

Determining the phase diagram of atomically thin layered antiferromagnet CrCl3

Valley polarization in monolayer CrX2 (X = S, Se) with magnetically doping and proximity coupling

Single-layer CrI3 grown by molecular beam epitaxy

Contact Info

Product

Resources

About

Atomically Thin CrCl₃: An In-Plane Layered Antiferromagnetic Insulator

Valley polarization in monolayer CrX₂ (X = S, Se) with magnetically doping and proximity coupling