Epitaxial Growth and Structural Characterizations of MnBi2Te4 Thin Films in Nanoscale

Abstract

The intrinsic magnetic topological insulator MnBi2Te4 has attracted much attention due to its special magnetic and topological properties. To date, most reports have focused on bulk or flake samples. For material integration and device applications, the epitaxial growth of MnBi2Te4 film in nanoscale is more important but challenging. Here, we report the growth of self-regulated MnBi2Te4 films by the molecular beam epitaxy. By tuning the substrate temperature to the optimal temperature for the growth surface, the stoichiometry of MnBi2Te4 becomes sensitive to the Mn/Bi flux ratio. Excessive and deficient Mn resulted in the formation of a MnTe and Bi2Te3 phase, respectively. The magnetic measurement of the 7 SL MnBi2Te4 film probed by the superconducting quantum interference device (SQUID) shows that the antiferromagnetic order occurring at the Néel temperature 22 K is accompanied by an anomalous magnetic hysteresis loop along the c-axis. The band structure measured by angle-resolved photoemission spectroscopy (ARPES) at 80 K reveals a Dirac-like surface state, which indicates that MnBi2Te4 has topological insulator properties in the paramagnetic phase. Our work demonstrates the key growth parameters for the design and optimization of the synthesis of nanoscale MnBi2Te4 films, which are of great significance for fundamental research and device applications involving antiferromagnetic topological insulators.

Superlattices of Gadolinium and Bismuth Based Thallium Dichalcogenides as Potential Magnetic Topological Insulators

“…In this sense, TlGdTe /(TlBiTe ) are somewhat similar to delta-doped systems, such as digital magnetic alloys [ 108 ], representing transition metal monolayers embedded in a matrix of semiconductor material, studied previously in the field of diluted magnetic semiconductors. We propose that TlGdTe /(TlBiTe ) can be synthesized using layer-by-layer growth techniques, such as molecular beam epitaxy or atomic layer deposition, that have proven successful for growing layered van der Waals and non-van der Waals materials, complex heterostructures and superlattices [ 32 , 56 , 109 , 110 , 111 ].…”

ARPES investigation of the electronic structure and its evolution in magnetic topological insulator MnBi2+2nTe4+3n family

“…The electronic structures of MnBi 2 Te 4 thin films grown by using MBE were systematically investigated by using ARPES [ 79 , 80 , 82–87 ]. Figure 7 shows the results collected using a 7-eV laser.…”

High-temperature magnetically topological candidate material Mn3Bi2Te6

“…For its bulk phase, MBT appears as a topologically non-trivial surface state on a surface with joint symmetry S = T τ , forming the so-called magnetic topological insulator (MTI) [6,7,9,28]. For MBT thin films, the peculiar phenomenon is demonstrated as Chern insulators in oddnumber layers and as axion insulators in even-number layers [13,14,16,17,29]. Previous researches demonstrate that the AFM transition temperature (T N ) of MBT is ∼25 K [6,7,9,10,13], which is too low to be widely applied in magnetic or spintronic devices at room temperature.…”