biostudies-literatureWimmer SSaint Petersburg State UniversityÖsterreichische ForschungsförderungsgesellschaftHelmholtz-GemeinschaftTomsk State UniversityAustrian Science Fund FWFVetenskapsrådetEuropean Research CouncilDeutsche ForschungsgemeinschaftMinisterstvo Školství, Mládeže a TělovýchovyStiftelsen för Strategisk Forskninge2102935https://www.ebi.ac.uk/biostudies/studies/S-EPMC11468489biostudies-literatureUnknown33(42)Ferromagnetic topological insulators exhibit the quantum anomalous Hall effect, which is potentially useful for high-precision metrology, edge channel spintronics, and topological qubits.  The stable 2+ state of Mn enables intrinsic magnetic topological insulators. MnBi₂ Te₄ is, however, antiferromagnetic with 25 K Néel temperature and is strongly n-doped. In this work, p-type MnSb₂ Te₄ , previously considered topologically trivial, is shown to be a ferromagnetic topological insulator for a few percent Mn excess. i) Ferromagnetic hysteresis with record Curie temperature of 45-50 K, ii) out-of-plane magnetic anisotropy, iii) a 2D Dirac cone with the Dirac point close to the Fermi level, iv) out-of-plane spin polarization as revealed by photoelectron spectroscopy, and v) a magnetically induced bandgap closing at the Curie temperature, demonstrated by scanning tunneling spectroscopy (STS), are shown. Moreover, a critical exponent of the magnetization β ≈ 1 is found, indicating the vicinity of a quantum critical point. Ab initio calculations reveal that Mn-Sb site exchange provides the ferromagnetic interlayer coupling and the slight excess of Mn nearly doubles the Curie temperature. Remaining deviations from the ferromagnetic order open the inverted bulk bandgap and render MnSb₂ Te₄ a robust topological insulator and new benchmark for magnetic topological insulators.Advanced materials (Deerfield Beach, Fla.)Mn-Rich MnSb<sub>2</sub> Te<sub>4</sub> : A Topological Insulator with Magnetic Gap Closing at High Curie Temperatures of 45-50 K.PMC1146848973028629LM2018110HRSF‐0067P 30960821‐2012‐5144I4493‐N: P30960‐N27RIF14‐00538.1.01.2018SPP1666Sanchez-Barriga JChulkov EVPrimetzhofer DRader OLake BFreyse FBihlmayer GWeschke EBauer GMichalicka JMorgenstern MWimmer SLiebmann MNey AHoffman MErnst ACaha OSchierle EOtrokov MMKuppers PSpringholz GfalseMn-Rich MnSb<sub>2</sub> Te<sub>4</sub> : A Topological Insulator with Magnetic Gap Closing at High Curie Temperatures of 45-50 K.Ferromagnetic topological insulators exhibit the quantum anomalous Hall effect, which is potentially useful for high-precision metrology, edge channel spintronics, and topological qubits.  The stable 2+ state of Mn enables intrinsic magnetic topological insulators. MnBi₂ Te₄ is, however, antiferromagnetic with 25 K Néel temperature and is strongly n-doped. In this work, p-type MnSb₂ Te₄ , previously considered topologically trivial, is shown to be a ferromagnetic topological insulator for a few percent Mn excess. i) Ferromagnetic hysteresis with record Curie temperature of 45-50 K, ii) out-of-plane magnetic anisotropy, iii) a 2D Dirac cone with the Dirac point close to the Fermi level, iv) out-of-plane spin polarization as revealed by photoelectron spectroscopy, and v) a magnetically induced bandgap closing at the Curie temperature, demonstrated by scanning tunneling spectroscopy (STS), are shown. Moreover, a critical exponent of the magnetization β ≈ 1 is found, indicating the vicinity of a quantum critical point. Ab initio calculations reveal that Mn-Sb site exchange provides the ferromagnetic interlayer coupling and the slight excess of Mn nearly doubles the Curie temperature. Remaining deviations from the ferromagnetic order open the inverted bulk bandgap and render MnSb₂ Te₄ a robust topological insulator and new benchmark for magnetic topological insulators.2021-01-01T00:00:00Z2021 Oct2025-04-04T13:53:56.099Z2025-04-04T13:53:56.099ZS-EPMC114684893446901310.1002/adma.202102935