Van der Waals engineering of ferromagnetic semiconductor heterostructures for spin and valleytronics

Zhong, Ding; Seyler, Kyle L.; Linpeng, Xiayu; Cheng, Ran; Sivadas, Nikhil; Huang, Bevin; Schmidgall, E. R.; Taniguchi, Takashi; Watanabe, Kenji; McGuire, Michael A.; Yao, Wang; Xiao, Di; Fu, Kai-Mei C.; Xu, Xiaodong

doi:10.1126/sciadv.1603113

Cited by 736 publications

(713 citation statements)

References 52 publications

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“…For many of the materials considered here, the in plane interactions are ferromagnetic (FM). Chromium trihalides were identified as some of the earliest ferromagnetic semiconductors, and CrX 3 compounds in general have received recent attention as candidate materials for the study of magnetic monolayers and for use in van der Waals heterostructures, in which their magnetism can be coupled to electronic and optical materials via proximity effects [14][15][16][17][18][19][20][21]. Developing cleavable ferroic materials, both magnetic and electric, is key to expanding the toolbox available for designing and creating custom, functional heterostructures and devices [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Crystal and Magnetic Structures in Layered, Transition Metal Dihalides and Trihalides

2017

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Materials composed of two dimensional layers bonded to one another through weak van der Waals interactions often exhibit strongly anisotropic behaviors and can be cleaved into very thin specimens and sometimes into monolayer crystals. Interest in such materials is driven by the study of low dimensional physics and the design of functional heterostructures. Binary compounds with the compositions MX 2 and MX 3 where M is a metal cation and X is a halogen anion often form such structures. Magnetism can be incorporated by choosing a transition metal with a partially filled d-shell for M, enabling ferroic responses for enhanced functionality. Here a brief overview of binary transition metal dihalides and trihalides is given, summarizing their crystallographic properties and long-range-ordered magnetic structures, focusing on those materials with layered crystal structures and partially filled d-shells required for combining low dimensionality and cleavability with magnetism.

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Section: Introductionmentioning

confidence: 99%

Crystal and Magnetic Structures in Layered, Transition Metal Dihalides and Trihalides

2017

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“…A large number of material parameters can be tuned by static perturbation of two-dimensional systems based on mechanically exfoliated nanoflakes or layer-by-layer epitaxy. Heterostructures offer pathways to induce energy gaps in the electronic structure by superlattice modulation, magnetic/superconducting proximity effects 35,36 , or even to generate giant pseudomagnetic fields (>300 T) with substrate defects all giving rise to striking …”

Section: Ways and Means Of Quantum Controlmentioning

confidence: 99%

Towards properties on demand in quantum materials

2017

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Q uantum materials are on the ascent. This term embodies a vast portfolio of compounds and phenomena where ramifications of quantum mechanics are demonstrably real. Quantum materials are in the vanguard of contemporary physics in part because these systems afford an exceptional venue to uncover the many roles of symmetry, topology, dimensionality and strong correlations in macroscopic observables. Here we set out to explore the ways and means of creating new states of matter in quantum materials and manipulating their phases via external stimuli. Practical control of these properties is a precondition for exploiting quantum advantages in new photonic, electronic and energy technologies, a task of significant societal impact 1 . We will primarily focus on the following classes of quantum materials: transition metal oxides, Fe-and Cu-based high-T c superconductors, van der Waals semiconductors, topological insulators and Weyl semimetals, and, finally, graphene.The properties of quantum materials are anomalously sensitive to external stimuli. In these systems, interactions associated with spin, charge, lattice and orbital degrees of freedom are commonly on par with the electronic kinetic energy. A rather fragile balance between coexisting and competing ground states can be readily shifted via external stimuli, leading to a raft of quantum phases and transitions between them 2,3 . Furthermore, certain classes of driven quantum states (Fig. 1a and Box 1) are explicit products of coherent interaction between light and matter 4-6 . Alternatively, the properties of quantum materials can be pre-programmed by directly manipulating the electronic wavefunction and the attendant Berry phase that give rise to the anomalous velocity of electrons in a solid [7][8][9] . These complementary avenues of controls mean that investigations no longer need to be reduced to merely observing (in contrast, for example, to astrophysics). Instead, it is now feasible to attain, in a predictable fashion, 'properties on demand' by steering a quantum material towards a desirable ground, metastable or transient state. The past decade has witnessed an explosion in the field of quantum materials, headlined by the predictions and discoveries of novel Landau-symmetry-broken phases in correlated electron systems, topological phases in systems with strong spin-orbit coupling, and ultra-manipulable materials platforms based on two-dimensional van der Waals crystals. Discovering pathways to experimentally realize quantum phases of matter and exert control over their properties is a central goal of modern condensed-matter physics, which holds promise for a new generation of electronic/photonic devices with currently inaccessible and likely unimaginable functionalities. In this Review, we describe emerging strategies for selectively perturbing microscopic interaction parameters, which can be used to transform materials into a desired quantum state. Particular emphasis will be placed on recent successes to tailor electronic interaction parameters through th...

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“…Recent interest in layered ferromagnetic materials is driven by the desire to develop functional van der Waals heterostructures [1,2]. For this purpose materials must be cleavable down to very thin, ideally monolayer, specimens.…”

Section: Introductionmentioning

confidence: 99%

“…All of * McGuireMA@ornl.gov the calculations predict low cleavage energies for these compounds, similar to those noted above for graphite and MoS 2 . Recently ferromagnetism has been experimentally confirmed in monolayer CrI 3 with intriguing thickness dependent magnetic phases [30], and heterostructures incorporating ultrathin CrI 3 have enabled remarkable control of the spin and valley pseudospin properties in monolayer WSe 2 through a large exchange field effect [2].…”

Section: Introductionmentioning

confidence: 99%

Magnetic behavior and spin-lattice coupling in cleavable van der Waals layered CrCl3 crystals

McGuire

Clark

et al. 2017

Phys. Rev. Materials

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CrCl3 is a layered insulator that undergoes a crystallographic phase transition below room temperature and orders antiferromagnetically at low temperature. Weak van der Waals bonding between the layers and ferromagnetic in-plane magnetic order make it a promising material for obtaining atomically thin magnets and creating van der Waals heterostructures. In this work we have grown crystals of CrCl3, revisited the structural and thermodynamic properties of the bulk material, and explored mechanical exfoliation of the crystals. We find two distinct anomalies in the heat capacity at 14 and 17 K confirming that the magnetic order develops in two stages on cooling, with ferromagnetic correlations forming before long range antiferromagnetic order develops between them. This scenario is supported by magnetization data. A magnetic phase diagram is constructed from the heat capacity and magnetization results. We also find an anomaly in the magnetic susceptibility at the crystallographic phase transition, indicating some coupling between the magnetism and the lattice. First principles calculations accounting for van der Waals interactions also indicate spin-lattice coupling, and find multiple nearly degenerate crystallographic and magnetic structures consistent with the experimental observations. Finally, we demonstrate that monolayer and few-layer CrCl3 specimens can be produced from the bulk crystals by exfoliation, providing a path for the study of heterostructures and magnetism in ultrathin crystals down to the monolayer limit.

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Van der Waals engineering of ferromagnetic semiconductor heterostructures for spin and valleytronics

Abstract: A van der Waals heterostructure of monolayer WSe2 and ferromagnetic CrI3 enables exceptional control of valley pseudospin.

Cited by 736 publications

References 52 publications

Crystal and Magnetic Structures in Layered, Transition Metal Dihalides and Trihalides

Crystal and Magnetic Structures in Layered, Transition Metal Dihalides and Trihalides

Towards properties on demand in quantum materials

Magnetic behavior and spin-lattice coupling in cleavable van der Waals layered CrCl3 crystals

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