Evolution of magnetic interactions in Sb-substituted 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>MnBi</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Te</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math>

Riberolles, S. X. M.; Zhang, Qiang; Gordon, Elijah E.; Butch, Nicholas P.; Ke, Liqin; Yan, Jiaqiang; McQueeney, R. J.

doi:10.1103/physrevb.104.064401

Cited by 38 publications

(35 citation statements)

References 32 publications

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“…Nevertheless, as shown in Supplementary Information, the presence of Bi Mn atoms is indeed confirmed by our structure refinement. The results of our structure characterizations are in agreement with the previous X-ray 28 and neutron 50,57 diffraction studies, as well as with the conclusions based on electron energy loss spectroscopy and transmission electron microscopy 12,55 . It is not surprising that the signatures of Bi Mn and Mn Bi lying in the fourth and sixth layers are not clearly seen on topographies as the tunneling probability depends drastically of the tip-sample distance.…”

Section: Figure 1dsupporting

confidence: 92%

“…In line with this, our STS measurements reveal that, depending on the sample cleavage, the local density of states is compatible with both large (∼50 meV) and small (<20 meV) DP gaps, in agreement with the laser-ARPES experiments, detecting that the DP gap changes from sample to sample. Our DFT surface electronic structure calculations show that the Mn Bi defects cause a strong reduction of the MnBi 2 Te 4 DP gap due to the antiparallel alignment of the Mn Bi moments with respect to those of the Mn layer [50][51][52] and predominant localization of the topological surface state near the Bi layers. We thus attribute the variation of the DP gap in the same sample (as observed by STS) or different samples (ARPES) to a different degree of the defectness of the MnBi 2 Te 4 crystals at local or global structure level, respectively.…”

Section: Introductionmentioning

confidence: 84%

“…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 . This is completely analogous to what is observed in MnSb 2 Te 4 50,51 , which is a related isostructural compound 4,23,24 .…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, recent neutron diffraction measurements reported in Refs. 50,57 detect Mn Bi atoms, too. Thus, we attribute the triangular-shaped depressions to the Mn Bi substitutions in the subsurface layer.…”

Section: Figure 1dmentioning

confidence: 99%

“…Importantly, since the defects in the second, fourth, and sixth layers essentially involve Mn, they cause deviations of the magnetic structure from the ideal one (shown in Figs. 1a-c) to a ferrimagnetic [50][51][52] , which might influence the DP gap size. In line with this, our STS measurements reveal that, depending on the sample cleavage, the local density of states is compatible with both large (∼50 meV) and small (<20 meV) DP gaps, in agreement with the laser-ARPES experiments, detecting that the DP gap changes from sample to sample.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Figure 1dsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Figure 1dmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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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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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Role of Magnetic Defects in Tuning Ground States of Magnetic Topological Insulators

et al. 2023

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Magnetic defects play an important, but poorly understood, role in magnetic topological insulators (TIs). For example, topological surface transport and bulk magnetic properties are controlled by magnetic defects in Bi2Se3‐based dilute ferromagnetic (FM) TIs and MnBi2Te4 (MBT)‐based antiferromagnetic (AFM) TIs. Despite its nascent ferromagnetism, the inelastic neutron scattering data show that a fraction of the Mn defects in Sb2Te3 form strong AFM dimer singlets within a quintuple block. The AFM superexchange coupling occurs via Mn–Te–Mn linear bonds and is identical to the AFM coupling between antisite defects and the FM Mn layer in MBT, establishing common interactions in the two materials classes. It is also found that the FM correlations in (Sb1−xMnx)2Te3 are likely driven by magnetic defects in adjacent quintuple blocks across the van der Waals gap. In addition to providing answers to long‐standing questions about the evolution of FM order in dilute TI, these results also show that the evolution of global magnetic order from AFM to FM in Sb‐substituted MBT is controlled by defect engineering of the intrablock and interblock coupling.

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Evolution of magnetic interactions in Sb-substituted MnBi2Te4

Cited by 38 publications

References 32 publications

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

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

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

Role of Magnetic Defects in Tuning Ground States of Magnetic Topological Insulators

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Evolution of magnetic interactions in Sb-substituted MnBi2Te4

Cited by 38 publications

References 32 publications

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

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

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

Role of Magnetic Defects in Tuning Ground States of Magnetic Topological Insulators

Contact Info

Product

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