Magnetic topological insulators

Tokura, Y.; Yasuda, K.; Tsukazaki, Atsushi

doi:10.1038/s42254-018-0011-5

Cited by 915 publications

(662 citation statements)

References 168 publications

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“…Interplay between electron-electron (el-el) correlation and spin-orbit coupling (SOC) in quantum matters can stimulate numerous intriguing correlated topological phases (1,2), such as spin-orbitalcoupled Mott insulator (3,4), Weyl semimetal (5,6), and Dirac semimetal (7,8). These exotic phases not only provide a fertile ground for discovering exotic topological physics but also hold great potential for electronic and spintronic devices with high tunability (9). In electronic systems with non-trivial topology, except for the topologically-protected edge/surface states, the physical properties and band structures are mostly presumed to be homogenous (10,11).…”

Section: Introductionmentioning

confidence: 99%

Controllable Thickness Inhomogeneity and Berry Curvature Engineering of Anomalous Hall Effect in SrRuO₃ Ultrathin Films

et al. 2020

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In quantum matters hosting electron-electron correlation and spin-orbit coupling, spatial inhomogeneities, arising from competing ground states, can be essential for determining and understanding topological properties. A prominent example is Hall anomalies observed in SrRuO 3 films, which were interpreted in terms of either magnetic skyrmion-induced topological Hall effect (THE) or inhomogeneous anomalous Hall effect (AHE). To clarify this ambiguity, we systematically investigated the AHE of SrRuO 3 ultrathin films with controllable inhomogeneities in film thickness (t SRO ). By harnessing the step-flow growth of SrRuO 3 films, we induced microscopically-ordered stripes with oneunit-cell differences in t SRO . The resultant spatial distribution of momentum-space Berry curvatures enables a two-channel AHE, which shows hump-like anomalies similar to the THE and can be continuously engineered via sub-unit-cell control of t SRO . In these inhomogeneous SRO films, we microscopically identified a two-step magnetic switching and stripe-like ferromagnetic domains. These features are fingerprints for distinguishing the two-channel AHE from the skyrmion-induced THE.

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Section: Introductionmentioning

confidence: 99%

Controllable Thickness Inhomogeneity and Berry Curvature Engineering of Anomalous Hall Effect in SrRuO₃ Ultrathin Films

et al. 2020

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“…Magnetic topological insulators (MTIs), which integrate both topology and magnetism within one system, have greatly broadened the research scope of quantum materials 1 . In addition to the spinmomentum locked feature of the non-trivial topological surface states, the introduction of perpendicular magnetic moments can also polarize the electron spins, and hence may possess a better capability for the control of the spin states within the host systems [2][3][4] .…”

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confidence: 99%

Tailoring the Hybrid Anomalous Hall Response in Engineered Magnetic Topological Insulator Heterostructures

Chen¹,

Zhang²,

Yao³

et al. 2020

Nano Lett.

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Engineering the anomalous Hall effect (AHE) in the emerging magnetic topological insulators (MTIs) has great potentials for quantum information processing and spintronics applications. In this letter, we synthesize the epitaxial Bi2Te3/MnTe magnetic heterostructures and observe pronounced AHE signals from both layers combined together. The evolution of the resulting hybrid AHE intensity with the top Bi2Te3 layer thickness manifests the presence of an intrinsic ferromagnetic phase induced by the topological surface states at the heterolayer-interface.More importantly, by doping the Bi2Te3 layer with Sb, we are able to manipulate the sign of the Berry phase-associated AHE component. Our results demonstrate the un-paralleled advantages of MTI heterostructures over magnetically doped TI counterparts, in which the tunability of the AHE response can be greatly enhanced. This in turn unveils a new avenue for MTI heterostructure-based multifunctional applications.3 Magnetic topological insulators (MTIs), which integrate both topology and magnetism within one system, have greatly broadened the research scope of quantum materials 1 . In addition to the spinmomentum locked feature of the non-trivial topological surface states, the introduction of perpendicular magnetic moments can also polarize the electron spins, and hence may possess a better capability for the control of the spin states within the host systems 2-4 . Therefore, introducing MTIs into the field of spintronics defines a new trend of magnetic-based logic and memory applications, in essence, to read and write the binary information that is encoded by the electron spin using all-electrical means.From a material point of view, a pronounced anomalous Hall effect (AHE) can be effectively generated in topological insulators (TIs) by magnetic doping 5-8 , and its quantum version (i.e., the quantum anomalous Hall effect) has been realized where the dissipation-less chiral edge state is formed without applying the magnetic field 2-3, 8-11 . Alternatively, MTI can also be achieved by proximity coupling of a TI to a ferro-/antiferromagnetic material [12][13][14][15][16][17][18][19][20] . In such MTI heterostructures, the separation of topology and magnetism in different layers enables us to optimize each contribution independently. For instance, rich inter-/intra-layer exchange couplings could result in higher magnetic transition temperatures and desirable complex spin textures [18][19][20] . Meanwhile, because of the strong spin-orbit coupling nature, the giant spin-orbit torque (SOT) within the TI layer would permit highly efficient current-driven magnetization switching up to room temperature [21][22][23] . Accordingly, the structural engineering of MTI not only enriches the choice of materials that can be joint together, but also provides additional degrees of freedom to manipulate different physical orders.Furthermore, in terms of device applications, while the read operation is evaluated by the difference between the '1' and '0' states from the electrical feedback...

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“…Magnetic topological insulators belong to a promising class of materials that can host novel surface transport phenomena [1]. For example, the quantum anomalous Hall effect has been demonstrated by inducing long-range ferromagnetic (FM) order via the addition of small concentrations of magnetic ions into tetradymite topological insulators [2][3][4].…”

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Localized singlets and ferromagnetic fluctuations in the dilute magnetic topological insulator Sn0.95Mn0.05Te

et al. 2020

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The development of long-range ferromagnetic (FM) order in dilute magnetic topological insulators can induce dissipationless electronic surface transport via the quantum anomalous Hall effect. We measure the magnetic excitations in a prototypical magnetic topological crystalline insulator, Sn0.95Mn0.05Te, using inelastic neutron scattering. Neutron diffraction and magnetization data indicate that our Sn0.95Mn0.05Te sample has no FM long-range order above a temperature of 2 K. However, we observe slow, collective FM fluctuations (< 70 µeV), indicating proximity to FM order. We also find a series of sharp peaks originating from local excitations of antiferromagnetically (AF) coupled and isolated Mn-Mn dimers with JAF = 460 µeV. The simultaneous presence of collective and localized components in the magnetic spectra highlight different roles for substituted Mn ions, with competition between FM order and the formation of AF-coupled Mn-Mn dimers.

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Magnetic topological insulators

Cited by 915 publications

References 168 publications

Controllable Thickness Inhomogeneity and Berry Curvature Engineering of Anomalous Hall Effect in SrRuO₃ Ultrathin Films

Controllable Thickness Inhomogeneity and Berry Curvature Engineering of Anomalous Hall Effect in SrRuO₃ Ultrathin Films

Tailoring the Hybrid Anomalous Hall Response in Engineered Magnetic Topological Insulator Heterostructures

Localized singlets and ferromagnetic fluctuations in the dilute magnetic topological insulator Sn0.95Mn0.05Te

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Magnetic topological insulators

Cited by 915 publications

References 168 publications

Controllable Thickness Inhomogeneity and Berry Curvature Engineering of Anomalous Hall Effect in SrRuO3 Ultrathin Films

Controllable Thickness Inhomogeneity and Berry Curvature Engineering of Anomalous Hall Effect in SrRuO3 Ultrathin Films

Tailoring the Hybrid Anomalous Hall Response in Engineered Magnetic Topological Insulator Heterostructures

Localized singlets and ferromagnetic fluctuations in the dilute magnetic topological insulator Sn0.95Mn0.05Te

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Controllable Thickness Inhomogeneity and Berry Curvature Engineering of Anomalous Hall Effect in SrRuO₃ Ultrathin Films

Controllable Thickness Inhomogeneity and Berry Curvature Engineering of Anomalous Hall Effect in SrRuO₃ Ultrathin Films