Topological Phase Transitions Driven by Sn Doping in (Mn1−xSnx)Bi2Te4

Тарасов, А. В.; Makarova, T. P.; Estyunin, D. A.; Eryzhenkov, A. V.; Климовских, И. И.; Golyashov, V. A.; Кох, К. А.; Tereshchenko, O. E.; Shikin, A. M.

doi:10.3390/sym15020469

Cited by 10 publications

(6 citation statements)

References 40 publications

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“…Several studies [29][30][31][32][33] have demonstrated the synthesis of these crystals and confirmed the absence of additional substitution defects, as in the case of s substitution of Sb for Bi atoms.…”

Section: Introductionmentioning

confidence: 66%

Comparative Study of Magnetic Properties of (Mn$_{1-x}$A$_x^{IV}$)Bi2Te4 A$_x^{IV}$ = Ge, Pb, Sn

Estyunin¹,

Rybkina²,

Кох³

et al. 2023

Preprint

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We investigated the magnetic properties of antiferromagnetic (AFM) topological insulator MnBi$_2$Te$_4$ with partial substitution of Mn atoms by non-magnetic elements (A$_x^{IV}$ = Ge, Pb, Sn). Samples with various element concentrations (10-80%) were studied using SQUID magnetometry. The results demonstrate that, for all substitutes the type of magnetic ordering remains AFM, while the Nèel temperature (T$_N$) and spin-flop transition field (H$_{SF}$) decrease with increasing A$_x^{IV}$ = Ge, Pb, Sn concentration. The rate of decrease varies among the elements, being highest for Pb, followed by Sn and Ge. This behavior is attributed to combined effects of magnetic dilution and lattice parameter increase on magnetic properties, most prominent in (Mn$_{1−x}$Pb$_x$)Bi$_2$Te$_4$. Besides this, the linear approximation of experimental data of T$_N$ and H$_{SF}$ suggests higher magnetic parameters for pure MnBi$_2$Te$_4$ than observed experimentally, indicating the possibility of their non-monotonic variation at low concentrations and the potential for enhancing magnetic properties through doping MnBi$_2$Te$_4$ with small amounts of nonmagnetic impurities. Notably, the (Mn$_{1−x}$Pb$_x$)Bi$_2$Te$_4$ sample with 10% Pb substitution indeed exhibits increased magnetic parameters, which is also validated by local analyses using ARPES. Our findings shed light on tailoring the magnetic behavior of MnBi$_2$Te$_4$-based materials, offering insights for potential applications in device technologies.

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Section: Introductionmentioning

confidence: 66%

Comparative Study of Magnetic Properties of (Mn$_{1-x}$A$_x^{IV}$)Bi2Te4 A$_x^{IV}$ = Ge, Pb, Sn

Estyunin¹,

Rybkina²,

Кох³

et al. 2023

Preprint

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“…The observed decrease in the band gap, culminating in an apparent zero gap with increasing Ge concentration, and the formation of a plateau with a minimum band gap in the concentration range of 45-55%, followed by a transition to the electronic structure of Mn-doped GeBi 2 Te 4 (at 90%), is consistent with previously reported data in the literature. This pattern has been observed both in systems where Mn atoms are replaced by Ge atoms 37,38 , as well as for substitutions with other Group IV elements such as Sn 36 and Pb 39 . However, the underlying reason for the formation of the minimum band gap plateau remains unclear.…”

Section: (B)mentioning

confidence: 75%

“…However, there is another possibility of modulating the energy gap at the DP and reaching the TPT point through the partial replacement of Mn atoms with IV-group elements (Ge, Sn, Pb) [36][37][38][39][40][41][42] . In Refs [36][37][38] , it was shown that when Mn is replaced by Ge, Sn, or Pb atoms in the Mn 1−x A x Bi 2 Te 4 (A = Ge, Sn, Pb) compounds, the bulk band gap decreases with an increase in the concentration of the substituting atoms. The gap decreases to practically zero at substituting element concentrations of 40-50%, with a possible transition from the topological state to the Weyl semimetal (WSM) state.…”

Section: Introductionmentioning

confidence: 99%

Phase transitions, Dirac and WSM states in Mn1−xGexBi2Te4

Shikin,

Zaitsev,

Estyunina

et al. 2024

Preprint

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Using angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT), an experimental andtheoretical study of changes in the electronic structure (dispersion dependencies) and corresponding modification of the energyband gap at the Dirac point (DP) for topological insulator (TI) Mn1−xGexBi2Te4 have been carried out with gradual replacementof magnetic Mn atoms by non-magnetic Ge atoms when concentration of the latter was varied from 10% to 75%. It was shownthat when Ge concentration increases then the bulk band gap decreases and reaches zero plateau in the concentration range of45%–60% while non-topological surface states (TSS) are present and exhibit an energy splitting of 100 and 70 meV in differenttypes of measurements. It was also shown that TSS disappear from the measured band dispersions at a Ge concentrationof about 40%. DFT calculations of Mn1−xGexBi2Te4 band structure were carried out to identify the nature of observed banddispersion features and to analyze a possibility of magnetic Weyl semimetal state formation in this system. These calculationswere performed for both antiferromagnetic (AFM) and ferromagnetic (FM) ordering types while the spin-orbit coupling (SOC)strength was varied or a strain (compression or tension) along the c-axis was applied. Calculations show that two differentseries of topological phase transitions (TPTs) may be implemented in this system depending on the magnetic ordering. At AFMordering transition between TI and trivial insulator phase goes through the Dirac semimetal state, whereas for FM phase suchroute admits three intermediate states instead of one (TI — Dirac semimetal — Weyl semimetal — Dirac semimetal — trivialinsulator). Weyl points that form in FM system along the ΓZ direction annihilate when either the SOC strength decreases or asufficient tensile strain is applied, which is accompanied by the corresponding TPTs. Model calculations of local magneticordering influence in AFM Mn1−xGexBi2Te4 was carried out by alternating Mn layers and Ge-doped layers and showed that themagnetic Weyl semimetal state in this system is reachable at a Ge concentration of approximately 40% without application ofany external magnetic fields

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“…The criteria for the presence of a topological state is the inversion of the valence and conduction bands [ 1 ]. For MnBi

, it appears as a domination of the contribution of the Bi

states at the top edge of the valence band, and of the Te

states at the bottom edge of the conduction band [ 19 , 23 ]. Figure 3 e–h shows the calculated dispersion dependencies for different concentrations of Ge, in which the colour shows the difference in contributions of the Te

states and Bi

states (red and blue, respectively).…”

Section: Resultsmentioning

confidence: 99%

“…In this context, the other effective approach for altering the value of the energy gap involves the substitution of transition metal (Mn) atoms with non-magnetic elements. Specifically, elements such as Sn, Pb, and Ge have been investigated as potential substitutes for Mn due to their ability to form the desired ternary compounds, including SnBi

[ 18 , 19 ], PbBi

[ 20 ], and GeBi

[ 21 , 22 ], which possess crystal structures similar to MnBi

. Experimental findings have revealed that the replacement of Mn with either Pb [ 23 ], Sn [ 24 , 25 ] or Ge [ 26 , 27 ] not only reduces the magnetic moments of the system, but also induces variation in the band structure due to the changes in orbital composition of valence and conduction bands.…”

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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Topological Phase Transitions Driven by Sn Doping in (Mn1−xSnx)Bi2Te4

Cited by 10 publications

References 40 publications

Comparative Study of Magnetic Properties of (Mn$_{1-x}$A$_x^{IV}$)Bi2Te4 A$_x^{IV}$ = Ge, Pb, Sn

Comparative Study of Magnetic Properties of (Mn$_{1-x}$A$_x^{IV}$)Bi2Te4 A$_x^{IV}$ = Ge, Pb, Sn

Phase transitions, Dirac and WSM states in Mn1−xGexBi2Te4

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

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