Influence of Structural Parameters on the Electronic Structure of Topological Surface States in MnBi2Te4

Makarova, T. P.; Shikin, A. M.; Eryzhenkov, A. V.; Тарасов, А. В.

doi:10.1134/s1063776123050102

Cited by 4 publications

(3 citation statements)

References 40 publications

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“…It was verified that further increasing the -mesh density leads only to very weak changes in the electronic structure. As an unit cell we used the structure presented in the work 56 . The basis functions were taken as Bi8.0-s3p2d2f1, Te7.0-s3p2d2f1, Mn6.0-s3p2d1, Se7.0-s3p2d2f1 (the pseudopotential cutoff radius is followed by a basis set specification).…”

Section: Methodsmentioning

confidence: 99%

Topological phase transition in the antiferromagnetic topological insulator MnBi$$_2$$Te$$_4$$ from the point of view of axion-like state realization

Shikin,

Estyunina,

Eryzhenkov

et al. 2023

Sci Rep

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This work aims to study the conditions of topological phase transition (TPT) between the topological and trivial states in the antiferromagnetic topological insulator (AFM TI) MnBi$$_2$$ 2 Te$$_4$$ 4 and propose some theory about the relationship of this TPT with the possibility of axion-like state realization in this material. Using the density functional approach we have analyzed the changes in the electronic and spin structure of topological surface states (TSSs) and the nearest conduction and valence bands (CB and VB) including the changes in the bulk band gap as well as the Dirac point (DP) gap in TSSs under variation of the spin-orbit coupling strength in the region of the TPT for infinite crystal and slab with a surface both. We have shown that in both cases the TPT occurs with inversion of the contributions of the Bi-$$p_z$$ p z and Te-$$p_z$$ p z states of different parity at the gap edges related to change in the gap sign. In the case of surface calculations, the Bi-$$p_z$$ p z and Te-$$p_z$$ p z states at the edges of the bulk band gap and their inversion at the TPT point are transformed into the TSSs with an energy gap at the DP. In this case the TPT takes place without closing the band gap, i.e. with a “jump” through zero and the formation of the nonzero gap during such a transition. Our calculations show that the TPT point is also characterized by an inversion of the out-of-plane spin polarization $$s_z$$ s z at the $$\Gamma$$ Γ point for lower and upper parts of the Dirac cone and a significant spatial redistribution of the TSSs between the surface and the bulk. We suppose that the nonzero Dirac gap can have some relationship with the formation of the axion-like state, which presumably couples nonmagnetic spin-orbit and magnetic contributions at the boundary between the topological and trivial phases for a system with parameters close to the TPT conditions. A practically realized system is proposed - the AFM TI with a stoichiometry close to that of MnBi$$_2$$ 2 Te$$_2$$ 2 Se$$_2$$ 2 with partial (about 50%) substitution of Te atoms for Se atoms in MnBi$$_2$$ 2 Te$$_4$$ 4 which can be an experimental platform for the implementation and experimental analysis of the TPT and the corresponding possibility of the axion-like state realization in Condensed Matter. Besides, such system could serve as a good platform for studying the dynamic axion effect, where the axion field fluctuations are maximised when a small external field is applied to the system which state is close to the TPT.

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Section: Methodsmentioning

confidence: 99%

Topological phase transition in the antiferromagnetic topological insulator MnBi$$_2$$Te$$_4$$ from the point of view of axion-like state realization

Shikin,

Estyunina,

Eryzhenkov

et al. 2023

Sci Rep

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“…The surface calculations were performed using 6 SLs slabs of MnBi

separated by 12

of vacuum. As an unit cell we used the structure presented in the work [ 16 ]. For the impurity calculations,

slab supercells were employed, which allow to consider four non-equivalent positions of Mn atoms within each layer.…”

Section: Methodsmentioning

confidence: 99%

“…A number of works have been devoted to the theoretical investigation of the factors that influence the energy gap [ 11 , 12 , 13 ]. For instance, a number of works demonstrated that the modulation of the energy gap value is achievable by modifying the surface van der Waals interval in TI crystals [ 14 , 15 , 16 ]. Furthermore, the modulation of the spin–orbit coupling (SOC) value has proven to be an efficacious approach [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Evolution of Mn1−xGexBi2Te4 Electronic Structure under Variation of Ge Content

Estyunina,

Shikin,

Estyunin

et al. 2023

Nanomaterials

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One of the approaches to manipulate MnBi2Te4 properties is the magnetic dilution, which inevitably affects the interplay of magnetism and band topology in the system. In this work, we carried out angle-resolved photoemission spectroscopy (ARPES) measurements and density functional theory (DFT) calculations for analysing changes in the electronic structure of Mn1−xGexBi2Te4 that occur under parameter x variation. We consider two ways of Mn/Ge substitution: (i) bulk doping of the whole system; (ii) surface doping of the first septuple layer. For the case (i), the experimental results reveal a decrease in the value of the bulk band gap, which should be reversed by an increase when the Ge concentration reaches a certain value. Ab-initio calculations show that at Ge concentrations above 50%, there is an absence of the bulk band inversion of the Te pz and Bi pz contributions at the Γ-point with significant spatial redistribution of the states at the band gap edges into the bulk, suggesting topological phase transition in the system. For case (ii) of the vertical heterostructure Mn1−xGexBi2Te4/MnBi2Te4, it was shown that an increase of Ge concentration in the first septuple layer leads to effective modulation of the Dirac gap in the absence of significant topological surface states of spatial redistribution. The results obtained indicate that surface doping compares favorably compared to bulk doping as a method for the Dirac gap value modulation.

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Modification of Topological Surface States in Novel Mn1 – xAxBi2Te4/MnBi2Te4 (A = Si, Ge, Sn, Pb) Topological Systems

Estyunina,

Tarasov,

Eryzhenkov

et al. 2024

Jetp Lett.

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Influence of Structural Parameters on the Electronic Structure of Topological Surface States in MnBi2Te4

Cited by 4 publications

References 40 publications

Topological phase transition in the antiferromagnetic topological insulator MnBi$$_2$$Te$$_4$$ from the point of view of axion-like state realization

Topological phase transition in the antiferromagnetic topological insulator MnBi$$_2$$Te$$_4$$ from the point of view of axion-like state realization

Evolution of Mn1−xGexBi2Te4 Electronic Structure under Variation of Ge Content

Modification of Topological Surface States in Novel Mn1 – xAxBi2Te4/MnBi2Te4 (A = Si, Ge, Sn, Pb) Topological Systems

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