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Irremovable Mn-Bi Site Mixing in MnBi
Xi Wu1,2, Chao Ruan1, Peizhe Tang3,4
1Shenzhen Geim Graphene Center and Institute of Materials Research, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, People's Republic of China.
Nano Letters
|June 5, 2023
Summary
Antiferromagnetic topological insulator MnBi2Te4 exhibits defects like MnBi and BiMn, hindering large-gap surface states. Complete defect elimination via annealing is difficult, impacting topological properties.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Materials
Background:
- MnBi2Te4 is an antiferromagnetic topological insulator with theoretically predicted gapped surface states.
- Experimental observations show smaller or gapless surface states, attributed to defects.
Purpose of the Study:
- Identify dominant defects in MnBi2Te4.
- Investigate defect evolution during phase transition.
- Explain the discrepancy between theoretical and experimental surface states.
Main Methods:
- Theoretical identification of antisite MnBi and BiMn defects.
- Analysis of defect evolution during MnTe/Bi2Te3 to MnBi2Te4 phase transition.
- Modeling the impact of defect concentration on surface state band gaps.
Main Results:
- Antisite MnBi and BiMn identified as dominant defects.
- Complete elimination of these defects by annealing is kinetically hindered.
- Increasing defect concentration closes the band gap of surface states.
Conclusions:
- Defects significantly impact the topological properties of MnBi2Te4.
- The presence of MnBi and BiMn defects explains the absence of large-gap surface states experimentally.
- Provides theoretical insights for synthesizing high-quality MnBi2Te4.
