Elucidating the Topological Nature of MBE Grown High T_C(MnSb₂Te₄)_x(Sb₂Te₃)_1-xUsing ARPES

Novel quantum phenomena emerging from the interplay between magnetism and nontrivial band topology in low-dimensional quantum materials of the Mn(X)₂Te₄ family (X = Bi, Sb, or a combination of both) are of intense current research interest. The most studied materials are MnBi₂Te₄ and MnSb₂Te₄ which support antiferromagnetic (AFM) order in the stoichiometric form but can be also grown as ferromagnets (FM) when antisite disorder is abundant, which is the case of MnSb₂Te₄. It has been recently shown that the Curie temperature (T_C) for structures of (MnSb₂Te₄)_x(Sb₂Te₃)_1-x depend on the composition x of the samples grown by molecular beam epitaxy (MBE). For x ≥ 0.75, values of T_C above 100 K are observed, the highest reported for these materials [1]. However, their topological nature has not yet been established. Here, we report investigations of (MnSb₂Te₄)_x(Sb₂Te₃)_1-x, with x = 1, and x = 0.80, and Mn(Sb,Bi)₂Te₄ using Angle-Resolved Photoemission Spectroscopy (ARPES) with photon energies between 24 eV and 80 eV. A shift in the position of the Fermi level between the samples with x = 1 and x = 0.8 consistent with reduced p-type doping at x = 1 is detected. Temperature-dependent ARPES was used to track changes in the band structure during the magnetic transition. The prominent bulk band ARPES features of these p-type materials as well as faint Dirac cone bands were identified, all consistent with the magnetic topological band structure. The DFT calculations rationalizing our ARPES results will be presented.



[1] C. R. Forrester et al., APL Mater. 12, 071109 (2024)