Speaker
Description
Design and synthesis of new quantum materials is a high-priority task of modern materials science and condensed matter physics. New classes of high-temperature superconductors, anisotropic magnetic materials and topological insulators may push forward electronics, spintronics, energy-saving technologies and information processing. Of particular interest are inorganic materials that belong to several such classes, e.g. the (MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_n$, $n$ = 0, 1, 2, 3 family that combines properties of topological insulators and quasi-2D magnetic van der Waals compounds [1, 2].
We have developed crystal-growth protocols of (MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_n$ based on the combined output from powder X-ray diffraction experiments and differential scanning calorimetry [3-5]. These crystals enabled the first experimental characterization of their magnetic, transport and topological properties. (MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_n$ are the first intrinsically magnetic topological insulators, whose (001) surfaces exhibit exotic spin-resolved surface states below the critical temperature (T$_N$ = 25 K for $n$ = 0, T$_N$ = 11-13 K for $n$ = 1-3).
These materials in their magnetically ordered state are a promising platform for quantum anomalous Hall effect [6]. Hence an increase of the magnetic ordering temperature and manipulation of the magnetic ground state via chemical and structural modifications are the most pertinent materials-specific optimization tasks. We report synthesis, crystal structure and magnetization studies of an isostructural analogue, MnSb$_2$Te$_4$, which is ferromagnetic up to a notably higher T$_C$ = 42 K. Another recently published study characterizes MnSb$_2$Te$_4$ as a ferrimagnet with T$_C$ = 25 K [7]. We discuss its magnetic ground state as elucidated by first-principles calculations and magnetization experiments, and investigate its connection with the Mn/Sb cation intermixing.
References
[1] Nature Rev. Phys. 1 (2019), 126.
[2] Nature 563 (2018), 47.
[3] Nature 576 (2019), 416.
[4] Chem. Mater. 31 (2019), 2795.
[5] Phys. Rev. X 9 (2019), 041065.
[6] Science 367 (2020), 895.
[7] Phys. Rev. B 100 (2019), 195103.
| Speaker Country | Netherlands |
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