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Magnetic Dirac semimetal state of (Mn,Ge)Bi2Te4

  • Alexander S. Frolov
  • , Dmitry Yu Usachov
  • , Artem V. Tarasov
  • , Alexander V. Fedorov
  • , Kirill A. Bokai
  • , Ilya Klimovskikh
  • , Vasily S. Stolyarov
  • , Anton I. Sergeev
  • , Alexander N. Lavrov
  • , Vladimir A. Golyashov
  • , Oleg E. Tereshchenko
  • , Giovanni Di Santo
  • , Luca Petacсia
  • , Oliver J. Clark
  • , Jaime Sanchez-Barriga
  • , Lada V. Yashina

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The ability to finely tune the properties of magnetic topological insulators (TIs) is crucial for quantum electronics. We studied solid solutions with a general formula GexMn1-xBi2Te4 between two isostructural Z2 TIs, magnetic MnBi2Te4 and nonmagnetic GeBi2Te4 with Z2 invariants of 1;000 and 1;001, respectively. We observed linear x-dependent magnetic properties, composition-independent pairwise exchange interactions, and topological phase transitions (TPTs) between topologically nontrivial phases and the semimetal state. The TPTs are driven purely by the variation of orbital contributions. By tracing the x-dependent Bi 6p contribution to the states near the fundamental gap, the effective spin-orbit coupling variation is extracted. The gapless state observed at x = 0.42 closely resembles a Dirac semimetal above the Néel temperature and shows a magnetic gap below, which is clearly visible in raw photoemission data. The observed behavior demonstrates an ability to precisely control topological and magnetic properties of TIs.

Original languageEnglish
Article number180
Number of pages11
JournalCommunications Physics
Volume7
Issue number1
DOIs
Publication statusPublished - 5 Jun 2024
Externally publishedYes

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