Observation of Quantum Anomalous Hall Effect and Exchange Interaction in Topological Insulator/Antiferromagnet Heterostructure

Pan, Lei; Grutter, Alexander J.; Zhang, Peng; Che, Xiaoyu; Nozaki, Tomohiro; Stern, Abraham C.; Street, Mike; Zhang, Bing; Casas, Brian; He, Qinglin; Choi, E. S.; Disseler, Steven M.; Gilbert, Dustin A.; Yin, Gen; Shao, Qiming; Deng, Peng; Wu, Yingying; Liu, Xiaoyang; Kou, Xufeng; Sahashi, M.; Han, Xiaodong; Binek, Ch.; Chambers, Scott A.; Xia, Jing; Wang, Kanglong

doi:10.1002/adma.202001460

Cited by 36 publications

(42 citation statements)

References 28 publications

(31 reference statements)

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“…erg. While the magnitude of the exchange bias eld observed here is comparable to what has been previously reported in the Cr 2 O 3 /CBST system, [31] the size of J eb is three orders of magnitude smaller than typical perpendicularly exchange-biased FM/AFM systems such as [Pt/Co]/Cr 2 O 3 and [Pt/Co]/IrMn, where the exchange couplings are believed to be short-range interactions. [32,33] In summary, we have studied the magnetization dynamics of Cr 0.26 (Bi 0.3 Sb 0.7 ) 1.74 Te 3 /CrSb bilayer system using ultrafast magneto-optical techniques.…”

Section: Discussionsupporting

confidence: 80%

Ultrafast Optical Control of Surface and Bulk Magnetism in Magnetic Topological Insulator/Antiferromagnet Heterostructure

Liu

Eckberg

Pan

et al. 2022

Preprint

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Optical control of the magnetic properties in topological insulator systems is an important step in applying these materials in ultrafast optoelectronic and spintronic schemes. In this work, we report the experimental observation of photo-induced magnetization dynamics in the magnetically doped topological insulator (MTI)/antiferromagnet (AFM) heterostructure composed of Cr-(Bi,Sb)2Te3/CrSb. Through proximity coupling to the AFM layer, the MTI displays a dramatically enhanced magnetism, with robust perpendicular magnetic anisotropy. When subjected to intense laser irradiation, magnetism in the bulk of the MTI is strikingly weakened by laser-induced heating of the lattice, whereas the surface magnetism is enhanced due to the strengthening Dirac-hole-mediated exchange coupling as demonstrated by an unconventional pump-fluence-dependent exchange-bias effect. Through theoretical analyses, the sizes of exchange coupling energies are estimated in the MTI/AFM bilayer structure. The fundamentally different mechanisms supporting the surface and bulk magnetic order in MTIs allow a novel and distinctive photo-induced transient magnetic state with antiparallel spin configuration, which broadens the understanding of the magnetization dynamics of MTIs under ultrashort and intense optical excitation.

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Section: Discussionsupporting

confidence: 80%

Ultrafast Optical Control of Surface and Bulk Magnetism in Magnetic Topological Insulator/Antiferromagnet Heterostructure

Liu

Eckberg

Pan

et al. 2022

Preprint

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“…[ 204 ] However, the heterostructure effectively engineers a long‐range exchange coupling between the MTI layers using the AFM layer with Néel temperature up to ≈700 K. Heterostructure of AFM and MTI may also lead to additional manipulation of the quantum anomalous Hall insulator (QAHI) state through exchange bias effect. [ 205 ]…”

Section: Recent Results In Topological Insulator (Ti) – Magnetic Materials (Mm) Heterostructuresmentioning

confidence: 99%

Recent Progress in Proximity Coupling of Magnetism to Topological Insulators

et al. 2021

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Inducing long‐range magnetic order in 3D topological insulators can gap the Dirac‐like metallic surface states, leading to exotic new phases such as the quantum anomalous Hall effect or the axion insulator state. These magnetic topological phases can host robust, dissipationless charge and spin currents or unique magnetoelectric behavior, which can be exploited in low‐energy electronics and spintronics applications. Although several different strategies have been successfully implemented to realize these states, to date these phenomena have been confined to temperatures below a few Kelvin. This review focuses on one strategy: inducing magnetic order in topological insulators by proximity of magnetic materials, which has the capability for room temperature operation, unlocking the potential of magnetic topological phases for applications. The unique advantages of this strategy, the important physical mechanisms facilitating magnetic proximity effect, and the recent progress to achieve, understand, and harness proximity‐coupled magnetic order in topological insulators are discussed. Some emerging new phenomena and applications enabled by proximity coupling of magnetism and topological materials, such as skyrmions and the topological Hall effect, are also highlighted, and the authors conclude with an outlook on remaining challenges and opportunities in the field.

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“…Recently, by further optimizing the interfacial magnetic proximity effect, the quantum anomalous Hall effect with tunable Chern numbers has also been realized in the emergent MTI heterostructures [65][66][67]]. Following the concept of magnetic insulator with non-zero Chern number elaborated in Section 1, a novel FMI/TI/FMI sandwich heterostructure of (Zn,Cr)Te/(Bi,Sb) 2 Te 3 /(Zn,Cr)Te is grown by MBE, as illustrated in Figure 8a [66].…”

Section: Towards High-t C Topological Insulators-based Magnetic Heterostructuresmentioning

confidence: 99%

“…The resulting strong magnetic exchange interaction at both TI/FMI interface thereafter opens the exchange gap of the TI surface states, and gives rise to the dissipationless chiral edge conduction when all dissipative channels in the (Zn,Cr)Te and (Bi,Sb) 2 Te 3 bulk layers are suppressed at 30 mK (Figure 8b). Additionally, the preparation of single-crystalline Cr 2 O 3 thin film with perpendicular spin-polarized surface by MBE can also introduce highly efficient interfacial exchange coupling in the Cr-doped (Bi x Sb 1−x ) 2 Te 3 /Cr 2 O 3 bilayer sample (Figure 8c) [65]. Consequently, the induced exchange bias effect provides another degree of freedom to manipulate the QAH states in the TI-based magnetic heterostructures.…”

Section: Towards High-t C Topological Insulators-based Magnetic Heterostructuresmentioning

confidence: 99%

Topological insulators-based magnetic heterostructures

Yao

Chen

et al. 2021

Advances in Physics: X

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The combination of magnetism and topology in magnetic topological insulators (MTIs) has led to unprecedented advancements of time reversal symmetry-breaking topological quantum physics in the past decade. Compared with the uniform films, the MTI heterostructures provide a better framework to manipulate the spin-orbit coupling and magnetic/spin properties. In this review, we summarize the fundamental mechanisms related to the physical orders host in (Bi,Sb) 2 (Te,Se) 3 -based hybrid systems. Besides, we provide an assessment on the general strategies to enhance the magnetic coupling and spin-orbit torque strength through different structural engineering approaches and effective interfacial interactions. Finally, we offer an outlook of MTI heterostructures-based spintronics applications, particularly in view of their feasibility to achieve room-temperature operation.

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Observation of Quantum Anomalous Hall Effect and Exchange Interaction in Topological Insulator/Antiferromagnet Heterostructure

Cited by 36 publications

References 28 publications

Ultrafast Optical Control of Surface and Bulk Magnetism in Magnetic Topological Insulator/Antiferromagnet Heterostructure

Ultrafast Optical Control of Surface and Bulk Magnetism in Magnetic Topological Insulator/Antiferromagnet Heterostructure

Recent Progress in Proximity Coupling of Magnetism to Topological Insulators

Topological insulators-based magnetic heterostructures

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