TY - JOUR

T1 - Evolution of Mn1−xGexBi2Te4 Electronic Structure under Variation of Ge Content

AU - Естюнина, Татьяна Павловна

AU - Шикин, Александр Михайлович

AU - Естюнин, Дмитрий Алексеевич

AU - Ерыженков, Александр Владимирович

AU - Климовских, Илья

AU - Бокай, Кирилл Андреевич

AU - Голяшов, Владимир Андреевич

AU - Кох, Константин Александрович

AU - Терещенко, Олег Евгеньевич

AU - Kumar, Shiv

AU - Shimada, Kenya

AU - Тарасов, Артем Вячеславович

PY - 2023/7/24

Y1 - 2023/7/24

N2 - 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.

AB - 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.

KW - ARPES

KW - ab-initio calculations

KW - electronic structure

KW - magnetic topological insulator

KW - topological phase transition

KW - topological surface states

KW - topological vertical heterostructure

UR - https://www.mendeley.com/catalogue/8db2bb4b-9397-3b8d-99a4-873e2d3afc27/

U2 - 10.3390/nano13142151

DO - 10.3390/nano13142151

M3 - Article

C2 - 37513162

VL - 13

JO - Nanomaterials

JF - Nanomaterials

SN - 2079-4991

IS - 14

M1 - 2151

ER -