Magnetized topological insulator multilayers

Lei, Chao; Chen, Shu; MacDonald, Allan H.

doi:10.1073/pnas.2014004117

Cited by 61 publications

(70 citation statements)

References 50 publications

(84 reference statements)

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“…These edge states provide the electron density of states for the observation of the gapless surface state in the ARPES experiment. A similar explanation is also proposed, 52 in which the directions of surface magnetic moments change in different terraces (domains). Consequently, topological edge states occur at the step edges of different terraces.…”

Section: Puzzle Of Surface States Of Mbtsupporting

confidence: 56%

“…Another route to regulating the properties of MBT is element substitution. 52,[85][86][87] Both magnetic and carrier properties are tunable by substituting Sb for Bi, and thus topological effects can be controlled by changing the proportion of Sb atoms in Mn(Sb x Bi 1Àx ) 2 Te 4 . 85,86 Yan et al 85 reported that, with increasing Sb content in Mn(Sb x Bi 1Àx ) 2 Te 4 , the Néel temperature decreased slightly from 24 K for MnBi 2 Te 4 to 19 K for MnSb 2 Te 4 , while the critical magnetic field strengths required for spin-flop transition and moment saturation decreased dramatically.…”

Section: Chemically Substituted Mbtmentioning

confidence: 99%

“…However, by applying a moderate magnetic field, bulk MBT becomes an FM WSM and thin-film FM MBT exhibits a Chern insulator band structure when the thickness is within the quantum confined regime, wherein the energy gap decreases and the Chern number may increase as the film gets thicker. 43 , 52 In other words, as a quantized system, thin-film FM MBT could have high Chern number ( C > 1) with increasing thickness. This unusual feature can be attributed to the combination of the quantum confinement effect and the WSM characteristics of the MBT FM phase, which paves a new way to realize high-Chern-number Chern insulators ( Figure 6 D).…”

Section: Observation Of Chern Insulator With High Working Temperature and High Chern Numbermentioning

confidence: 99%

“…Another route to regulating the properties of MBT is element substitution. 52 , 85 , 86 , 87 Both magnetic and carrier properties are tunable by substituting Sb for Bi, and thus topological effects can be controlled by changing the proportion of Sb atoms in Mn(Sb x Bi 1− x ) 2 Te 4 . 85 , 86 Yan et al .…”

Section: Mbt-related Systemsmentioning

confidence: 99%

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Intrinsic magnetic topological insulators

Wang

Zhang

et al. 2021

The Innovation

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van der Waals material MnBi 2 Te 4 is an intrinsic antiferromagnetic topological insulator -Under moderate magnetic field, MnBi 2 Te 4 may become a magnetic Weyl semimetal -MnBi 2 Te 4 and its family of materials have brought great progress in studying novel topological quantum states -Quantum anomalous Hall effect above the liquid-nitrogen temperature can be expected in MnBi 2 Te 4 -related systems ll www.cell.com/the-innovation

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Section: Puzzle Of Surface States Of Mbtsupporting

confidence: 56%

Section: Chemically Substituted Mbtmentioning

confidence: 99%

Section: Observation Of Chern Insulator With High Working Temperature and High Chern Numbermentioning

confidence: 99%

Section: Mbt-related Systemsmentioning

confidence: 99%

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Intrinsic magnetic topological insulators

Wang

Zhang

et al. 2021

The Innovation

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“…was discovered [14][15][16][17] and attracted extensive interest [18][19][20][21][22][23][24][25][26].…”

mentioning

confidence: 99%

Facet dependent surface energy gap on magnetic topological insulators

Tan,

Yan

2022

Preprint

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Magnetic topological insulators (MnBi 2 Te 4 )(Bi 2 Te 3 ) n (n = 0, 1, 2, 3) are promising to realize exotic topological states such as the quantum anomalous Hall effect (QAHE) and axion insulator (AI), where the Bi 2 Te 3 layer introduces versatility to engineer electronic and magnetic properties.However, whether surface states on the Bi 2 Te 3 terminated facet are gapless or gapped is debated, and its consequences in thin-film properties are rarely discussed. In this work, we find that the Bi 2 Te 3 terminated facets are gapless for n ≥ 1 compounds by calculations. Despite that the surface Bi 2 Te 3 (one layer or more) and underlying MnBi 2 Te 4 layers hybridize and give rise to a gap, such a hybridization gap overlaps with bulk valence bands, leading to a gapless surface after all. Such a metallic surface poses a fundamental challenge to realize QAHE or AI, which requires an insulating gap in thin films with at least one Bi 2 Te 3 surface. In theory, the insulating phase can still be realized in a film if both surfaces are MnBi 2 Te 4 layers. Otherwise, it requires that the film thickness is less than 10∼20 nm to push down bulk valence bands via the size effect. Our work paves the way to understand surface states and design bulk-insulating quantum devices in magnetic topological materials.

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Mn‐Rich MnSb₂Te₄: A Topological Insulator with Magnetic Gap Closing at High Curie Temperatures of 45–50 K

et al. 2021

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Ferromagnetic topological insulators exhibit the quantum anomalous Hall effect, which is potentially useful for high‐precision metrology, edge channel spintronics, and topological qubits. The stable 2+ state of Mn enables intrinsic magnetic topological insulators. MnBi2Te4 is, however, antiferromagnetic with 25 K Néel temperature and is strongly n‐doped. In this work, p‐type MnSb2Te4, previously considered topologically trivial, is shown to be a ferromagnetic topological insulator for a few percent Mn excess. i) Ferromagnetic hysteresis with record Curie temperature of 45–50 K, ii) out‐of‐plane magnetic anisotropy, iii) a 2D Dirac cone with the Dirac point close to the Fermi level, iv) out‐of‐plane spin polarization as revealed by photoelectron spectroscopy, and v) a magnetically induced bandgap closing at the Curie temperature, demonstrated by scanning tunneling spectroscopy (STS), are shown. Moreover, a critical exponent of the magnetization β ≈ 1 is found, indicating the vicinity of a quantum critical point. Ab initio calculations reveal that Mn–Sb site exchange provides the ferromagnetic interlayer coupling and the slight excess of Mn nearly doubles the Curie temperature. Remaining deviations from the ferromagnetic order open the inverted bulk bandgap and render MnSb2Te4 a robust topological insulator and new benchmark for magnetic topological insulators.

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Magnetized topological insulator multilayers

Cited by 61 publications

References 50 publications

Intrinsic magnetic topological insulators

Intrinsic magnetic topological insulators

Facet dependent surface energy gap on magnetic topological insulators

Mn‐Rich MnSb₂Te₄: A Topological Insulator with Magnetic Gap Closing at High Curie Temperatures of 45–50 K

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Magnetized topological insulator multilayers

Cited by 61 publications

References 50 publications

Intrinsic magnetic topological insulators

Intrinsic magnetic topological insulators

Facet dependent surface energy gap on magnetic topological insulators

Mn‐Rich MnSb2Te4: A Topological Insulator with Magnetic Gap Closing at High Curie Temperatures of 45–50 K

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Product

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Mn‐Rich MnSb₂Te₄: A Topological Insulator with Magnetic Gap Closing at High Curie Temperatures of 45–50 K