Phase transitions, Dirac and Weyl semimetal states in Mn1−x Ge x Bi2Te4
Abstract Using angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT), an experimental and theoretical study of changes in the electronic structure (dispersion dependencies) and corresponding modification of the energy band gap at the Dirac point (DP) for topological i...
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2025-01-01
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| Online Access: | https://doi.org/10.1038/s41598-024-73267-1 |
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| author | A. M. Shikin N. L. Zaitsev T. P. Estyunina D. A. Estyunin A. G. Rybkin D. A. Glazkova I. I. Klimovskikh A. V. Eryzhenkov K. A. Kokh V. A. Golyashov O. E. Tereshchenko S. Ideta Y. Miyai Y. Kumar T. Iwata T. Kosa K. Kuroda K. Shimada A. V. Tarasov |
| author_facet | A. M. Shikin N. L. Zaitsev T. P. Estyunina D. A. Estyunin A. G. Rybkin D. A. Glazkova I. I. Klimovskikh A. V. Eryzhenkov K. A. Kokh V. A. Golyashov O. E. Tereshchenko S. Ideta Y. Miyai Y. Kumar T. Iwata T. Kosa K. Kuroda K. Shimada A. V. Tarasov |
| author_sort | A. M. Shikin |
| collection | DOAJ |
| description | Abstract Using angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT), an experimental and theoretical study of changes in the electronic structure (dispersion dependencies) and corresponding modification of the energy band gap at the Dirac point (DP) for topological insulator (TI) $$\textrm{Mn}_{1-x} \textrm{Ge}_x \textrm{Bi}_2 \textrm{Te}_4$$ have been carried out with gradual replacement of magnetic Mn atoms by non-magnetic Ge atoms when concentration of the latter was varied from 10% to 75%. It was shown that when Ge concentration increases, the bulk band gap decreases and reaches zero plateau in the concentration range of 45–60% while trivial surface states (TrSS) are present and exhibit an energy splitting of 100 and 70 meV in different types of measurements. It was also shown that TSS disappear from the measured band dispersions at a Ge concentration of about 40%. DFT calculations of $$\textrm{Mn}_{1-x} \textrm{Ge}_x \textrm{Bi}_2 \textrm{Te}_4$$ band structure were carried out to identify the nature of observed band dispersion features and to analyze the possibility of magnetic Weyl semimetal state formation in this system. These calculations were 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 different series of topological phase transitions (TPTs) may be implemented in this system, depending on the magnetic ordering. In the case of AFM ordering, the transition between TI and the trivial insulator phase passes through the Dirac semimetal state, whereas for FM phase such route admits three intermediate states instead of one (TI—Dirac semimetal—Weyl semimetal—Dirac semimetal—trivial insulator). Weyl points that form in the FM system along the $$\varGamma \!Z$$ direction annihilate when either the SOC strength decreases or a sufficient tensile strain is applied, which is accompanied by the corresponding TPTs. Model calculations of the influence of local magnetic ordering in AFM $$\textrm{Mn}_{1-x} \textrm{Ge}_x \textrm{Bi}_2 \textrm{Te}_4$$ were carried out by alternating Mn layers with Ge-doped layers and showed that the magnetic Weyl semimetal state in this system is reachable at a Ge concentration of approximately 40% without application of any external magnetic fields. |
| format | Article |
| id | doaj-art-210fff17d70b4a50b8bc43dab70b3829 |
| institution | Kabale University |
| issn | 2045-2322 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Scientific Reports |
| spelling | doaj-art-210fff17d70b4a50b8bc43dab70b38292025-01-12T12:18:00ZengNature PortfolioScientific Reports2045-23222025-01-0115111910.1038/s41598-024-73267-1Phase transitions, Dirac and Weyl semimetal states in Mn1−x Ge x Bi2Te4A. M. Shikin0N. L. Zaitsev1T. P. Estyunina2D. A. Estyunin3A. G. Rybkin4D. A. Glazkova5I. I. Klimovskikh6A. V. Eryzhenkov7K. A. Kokh8V. A. Golyashov9O. E. Tereshchenko10S. Ideta11Y. Miyai12Y. Kumar13T. Iwata14T. Kosa15K. Kuroda16K. Shimada17A. V. Tarasov18Saint Petersburg State UniversitySaint Petersburg State UniversitySaint Petersburg State UniversitySaint Petersburg State UniversitySaint Petersburg State UniversitySaint Petersburg State UniversityDonostia International Physics Center (DIPC)Saint Petersburg State UniversitySaint Petersburg State UniversitySaint Petersburg State UniversitySaint Petersburg State UniversityResearch Institute for Synchrotron Radiation Science (HiSOR), Hiroshima UniversityResearch Institute for Synchrotron Radiation Science (HiSOR), Hiroshima UniversityResearch Institute for Synchrotron Radiation Science (HiSOR), Hiroshima UniversityGraduate School of Advanced Science and Engineering, Hiroshima UniversityGraduate School of Advanced Science and Engineering, Hiroshima UniversityGraduate School of Advanced Science and Engineering, Hiroshima UniversityResearch Institute for Synchrotron Radiation Science (HiSOR), Hiroshima UniversitySaint Petersburg State UniversityAbstract Using angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT), an experimental and theoretical study of changes in the electronic structure (dispersion dependencies) and corresponding modification of the energy band gap at the Dirac point (DP) for topological insulator (TI) $$\textrm{Mn}_{1-x} \textrm{Ge}_x \textrm{Bi}_2 \textrm{Te}_4$$ have been carried out with gradual replacement of magnetic Mn atoms by non-magnetic Ge atoms when concentration of the latter was varied from 10% to 75%. It was shown that when Ge concentration increases, the bulk band gap decreases and reaches zero plateau in the concentration range of 45–60% while trivial surface states (TrSS) are present and exhibit an energy splitting of 100 and 70 meV in different types of measurements. It was also shown that TSS disappear from the measured band dispersions at a Ge concentration of about 40%. DFT calculations of $$\textrm{Mn}_{1-x} \textrm{Ge}_x \textrm{Bi}_2 \textrm{Te}_4$$ band structure were carried out to identify the nature of observed band dispersion features and to analyze the possibility of magnetic Weyl semimetal state formation in this system. These calculations were 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 different series of topological phase transitions (TPTs) may be implemented in this system, depending on the magnetic ordering. In the case of AFM ordering, the transition between TI and the trivial insulator phase passes through the Dirac semimetal state, whereas for FM phase such route admits three intermediate states instead of one (TI—Dirac semimetal—Weyl semimetal—Dirac semimetal—trivial insulator). Weyl points that form in the FM system along the $$\varGamma \!Z$$ direction annihilate when either the SOC strength decreases or a sufficient tensile strain is applied, which is accompanied by the corresponding TPTs. Model calculations of the influence of local magnetic ordering in AFM $$\textrm{Mn}_{1-x} \textrm{Ge}_x \textrm{Bi}_2 \textrm{Te}_4$$ were carried out by alternating Mn layers with Ge-doped layers and showed that the magnetic Weyl semimetal state in this system is reachable at a Ge concentration of approximately 40% without application of any external magnetic fields.https://doi.org/10.1038/s41598-024-73267-1ARPESDFTMnBi2Te4Magnetic topological insulatorsWeyl semimetalsdoping |
| spellingShingle | A. M. Shikin N. L. Zaitsev T. P. Estyunina D. A. Estyunin A. G. Rybkin D. A. Glazkova I. I. Klimovskikh A. V. Eryzhenkov K. A. Kokh V. A. Golyashov O. E. Tereshchenko S. Ideta Y. Miyai Y. Kumar T. Iwata T. Kosa K. Kuroda K. Shimada A. V. Tarasov Phase transitions, Dirac and Weyl semimetal states in Mn1−x Ge x Bi2Te4 Scientific Reports ARPES DFT MnBi2Te4 Magnetic topological insulators Weyl semimetals doping |
| title | Phase transitions, Dirac and Weyl semimetal states in Mn1−x Ge x Bi2Te4 |
| title_full | Phase transitions, Dirac and Weyl semimetal states in Mn1−x Ge x Bi2Te4 |
| title_fullStr | Phase transitions, Dirac and Weyl semimetal states in Mn1−x Ge x Bi2Te4 |
| title_full_unstemmed | Phase transitions, Dirac and Weyl semimetal states in Mn1−x Ge x Bi2Te4 |
| title_short | Phase transitions, Dirac and Weyl semimetal states in Mn1−x Ge x Bi2Te4 |
| title_sort | phase transitions dirac and weyl semimetal states in mn1 x ge x bi2te4 |
| topic | ARPES DFT MnBi2Te4 Magnetic topological insulators Weyl semimetals doping |
| url | https://doi.org/10.1038/s41598-024-73267-1 |
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