The Layer-Inserting Growth of Antiferromagnetic Topological Insulator MnBi2Te4 Based on Symmetry and Its X-ray Photoelectron Spectroscopy

Jiao, Fei; Wang, Jingfeng; Wang, Xianyu; Tian, Qingyin; Chang, Meixia; Cai, Lingbo; Zhu, Shu; Zhang, Di; Lü, Qing; Wang, Cao; Tan, Shugang; Li, Yunlong; Jing, Qiang; Liu, Bo; Qian, Dong

doi:10.1007/s10948-021-05821-1

Cited by 8 publications

(5 citation statements)

References 55 publications

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“…[22] The low charge state of Mn was found to come from nanoclusters of manganese subtelluride induced by Ar + ion sputtering in MnTe film. [26,27] We prefer the Mn q+ (0 < q < 1) charge state may originate from the charge transfer between MnTe 2 film and the Si(111) substrate. Peak 2 of 641.9 eV belongs to the Mn-Te bonds of MnTe 2 .…”

Section: Resultsmentioning

confidence: 99%

Molecular beam epitaxy growth of monolayer hexagonal MnTe₂ on Si(111) substrate*

Lü¹,

Peng²,

Wang³

et al. 2021

Chinese Phys. B

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Monolayer MnTe2 stabilized as 1T structure has been theoretically predicted to be a two-dimensional (2D) ferromagnetic metal and can be tuned via strain engineering. There is no naturally van der Waals (vdW) layered MnTe2 bulk, leaving mechanical exfoliation impossible to prepare monolayer MnTe2. Herein, by means of molecular beam epitaxy (MBE), we successfully prepared monolayer hexagonal MnTe2 on Si(111) under Te rich condition. Sharp reflection high-energy electron diffraction (RHEED) and low-energy electron diffraction (LEED) patterns suggest the monolayer is atomically flat without surface reconstruction. The valence state of Mn4+ and the atom ratio of ([Te]:[Mn]) further confirm the MnTe2 compound. Scanning tunneling spectroscopy (STS) shows the hexagonal MnTe2 monolayer is a semiconductor with a large bandgap of ∼ 2.78 eV. The valence-band maximum (VBM) locates at the Γ point, as illustrated by angle-resolved photoemission spectroscopy (ARPES), below which three hole-type bands with parabolic dispersion can be identified. The successful synthesis of monolayer MnTe2 film provides a new platform to investigate the 2D magnetism.

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Section: Resultsmentioning

confidence: 99%

Molecular beam epitaxy growth of monolayer hexagonal MnTe₂ on Si(111) substrate*

Lü¹,

Peng²,

Wang³

et al. 2021

Chinese Phys. B

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“…Recent high-field magnetization measurements show that reaching the saturation magnetization of MnBi 2 Te 4 (corresponding to about 4.6 µ B per Mn) requires very large external magnetic fields of about 60 T 52 , while many previous studies revealed an incomplete saturation, ∼3 -3.8 µ B per Mn at about 6-7 T 7,12,13,15,19,67,68 . The reason for this has been found to be a "ferrimagnetic" structure of the septuple layer block, in which the local moments of the Mn Bi defects are coupled antiparallel to those of the central Mn layer 50,69 .…”

Section: Discussionmentioning

confidence: 96%

Native point defects and their implications for the Dirac point gap at MnBi$_2$Te$_4$(0001)

Garnica¹,

Otrokov²,

Aguilar³

et al. 2021

Preprint

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The Dirac point gap at the surface of the antiferromagnetic topological insulator MnBi2Te4 is a highly debated issue. While the early photoemission measurements reported on large gaps in agreement with theoretical predictions, other experiments found vanishingly small splitting of the MnBi2Te4 Dirac cone. Here, we study the crystalline and electronic structure of MnBi2Te4(0001) using scanning tunneling microscopy/spectroscopy (STM/S), micro(µ)-laser angle resolved photoemission spectroscopy (ARPES), and density functional theory (DFT) calculations. Our topographic STM images clearly reveal features corresponding to point defects in the surface Te and subsurface Bi layers that we identify with the aid of STM simulations as BiTe antisites (Bi atoms at the Te sites) and MnBi substitutions (Mn atoms at the Bi sites), respectively. X-ray diffraction (XRD) experiments further evidence the presence of cation (Mn-Bi) intermixing. Altogether, this affects the distribution of the Mn atoms, which, inevitably, leads to a deviation of the MnBi2Te4 magnetic structure from that predicted for the ideal crystal structure. Our transport measurements suggest that the degree of this deviation varies from sample to sample. Consistently, the ARPES/STS experiments reveal that the Dirac point gap of the topological surface state is different for different samples/sample cleavages. Our DFT surface electronic structure calculations show that, due to the predominant localization of the topological surface state near the Bi layers, MnBi defects can cause a strong reduction of the MnBi2Te4 Dirac point gap, given the recently proved antiparallel alignment of the MnBi moments with respect to those of the Mn layer. Our results provide a key to puzzle out the MnBi2Te4 Dirac point gap mystery.

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“…First, a large in-plane lattice mismatch,

, between VTe 2 and Bi 2 Te 3 might prohibit the formation of VBi 2 Te 4 [ 28 ]. Our STEM results indicate

= 0.83 Å between the two phases.…”

Section: Discussionmentioning

confidence: 99%

Phase Separation Prevents the Synthesis of VBi2Te4 by Molecular Beam Epitaxy

Altena,

Jansen,

Tsvetanova

et al. 2023

Nanomaterials

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Intrinsic magnetic topological insulators (IMTIs) have a non-trivial band topology in combination with magnetic order. This potentially leads to fascinating states of matter, such as quantum anomalous Hall (QAH) insulators and axion insulators. One of the theoretically predicted IMTIs is VBi2Te4, but experimental evidence of this material is lacking so far. Here, we report on our attempts to synthesise VBi2Te4 by molecular beam epitaxy (MBE). X-ray diffraction reveals that in the thermodynamic phase space reachable by MBE, there is no region where VBi2Te4 is stably synthesised. Moreover, scanning transmission electron microscopy shows a clear phase separation to Bi2Te3 and VTe2 instead of the formation of VBi2Te4. We suggest the phase instability to be due to either the large lattice mismatch between VTe2 and Bi2Te3 or the unfavourable valence state of vanadium.

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The Layer-Inserting Growth of Antiferromagnetic Topological Insulator MnBi2Te4 Based on Symmetry and Its X-ray Photoelectron Spectroscopy

Cited by 8 publications

References 55 publications

Molecular beam epitaxy growth of monolayer hexagonal MnTe₂ on Si(111) substrate*

Molecular beam epitaxy growth of monolayer hexagonal MnTe₂ on Si(111) substrate*

Native point defects and their implications for the Dirac point gap at MnBi$_2$Te$_4$(0001)

Phase Separation Prevents the Synthesis of VBi2Te4 by Molecular Beam Epitaxy

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The Layer-Inserting Growth of Antiferromagnetic Topological Insulator MnBi2Te4 Based on Symmetry and Its X-ray Photoelectron Spectroscopy

Cited by 8 publications

References 55 publications

Molecular beam epitaxy growth of monolayer hexagonal MnTe2 on Si(111) substrate*

Molecular beam epitaxy growth of monolayer hexagonal MnTe2 on Si(111) substrate*

Native point defects and their implications for the Dirac point gap at MnBi$_2$Te$_4$(0001)

Phase Separation Prevents the Synthesis of VBi2Te4 by Molecular Beam Epitaxy

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Product

Resources

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Molecular beam epitaxy growth of monolayer hexagonal MnTe₂ on Si(111) substrate*

Molecular beam epitaxy growth of monolayer hexagonal MnTe₂ on Si(111) substrate*