Abstract
We investigate the stability of MnPb2Bi2Te6 (MPBT), which is predicted to be a magnetic topological insulator (TI), using density functional theory calculations. Our analysis includes various measures such as enthalpies of formation, Helmholtz free energies, defect formation energies, and dynamical stability. Our thermodynamic analysis shows that the phonon contribution to the energy gain from finite temperature is estimated to be less than 10 meV/atom, which may not be sufficient to stabilize MPBT at high temperatures, even with the most favorable reactions starting from binaries. While MPBT is generally robust against the formation of various defects, we find that the anti-site defect formation of MnPb is the most likely to occur, with a corresponding energy less than 60 meV. This can be attributed to the significant energy cost from compressive strain at the PbTe layer. Our findings suggest that MPBT is on the brink of stability in terms of thermodynamics and defect formation, underscoring the importance of conducting systematic analyses of the stability of proposed TIs, including MPBT, for their practical utilization. This study offers valuable insights into the design and synthesis of desirable magnetic TI materials with robust stabilities.
| Original language | English |
|---|---|
| Pages (from-to) | 17021-17028 |
| Number of pages | 8 |
| Journal | Journal of Physical Chemistry C |
| Volume | 127 |
| Issue number | 34 |
| DOIs | |
| State | Published - Aug 31 2023 |
Funding
The authors would like to acknowledge the useful discussions with Jiaqiang Yan on the synthesis of new compounds. Work by S.H.K. (calculations, writing) was supported by the U.S. DOE, Office of Science, National Quantum Information Science Research Centers, Quantum Science Center (S.H.K.). Work by J.A. (calculations and writing) and J.T.K. (mentorship and writing) was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, as part of the Computational Materials Sciences Program and Center for Predictive Simulation of Functional Materials. Work by M.H.D., M.Y., and F.A.R. (original idea, mentorship, and writing) was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. An award of computer time was provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. This research used resources of the Oak Ridge Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE- AC05-00OR22725. This research also used the resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under Contract no. DE-AC02-05CH11231.