Antiferromagnetic topological insulator MnBi₂Te₄: synthesis and magnetic properties

Abstract

Recently, MnBi2Te4 has been discovered as the first intrinsic antiferromagnetic topological insulator (AFM TI), and will become a promising material to discover exotic topological quantum phenomena. In this work, we have realized the successful synthesis of high-quality MnBi2Te4 single crystals by solid-state reactions. The as-grown MnBi2Te4 single crystal exhibits a van der Waals layered structure, which is composed of septuple Te-Bi-Te-Mn-Te-Bi-Te sequences as determined by powder X-ray diffraction (PXRD) and high-resolution high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). The magnetic order below 25 K as a consequence of A-type antiferromagnetic interaction between Mn layers in the MnBi2Te4 crystal suggests the unique interplay between antiferromagnetism and topological quantum states. The transport measurements of MnBi2Te4 single crystals further confirm its magnetic transition. Moreover, the unstable surface of MnBi2Te4, which is found to be easily oxidized in air, deserves attention for onging research on few-layer samples. This study on the first AFM TI of MnBi2Te4 will guide the future research on other potential candidates in the MBixTey family (M = Ni, V, Ti, etc.).

MnBi2Te4-family intrinsic magnetic topological materials

“…Rapid and exciting experimental progress has been made in MnBi 2 Te 4 -family materials in the past years, constructing one of the hottest topics in condensed matter physics recently 8,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] . Single-crystal samples of MnBi 2 Te 4 -family materials have been successfully prepared by several groups [20][21][22][23][24][25][26][27] . The A-type AFM structure has been demonstrated with SQUID measurements and directly observed with magnetic force microscopy 28,29 .…”

Selenium‐Based Solar Cell with Conjugated Polymers as Both Electron and Hole Transport Layers to Realize High Water Tolerance as well as Good Long‐Term and Thermal Stability

“…ITO is highly water-resistant because one necessary step to clean ITO in solar cell fabrication process is immersing in water under ultrasonic. [9,30] The polymer ETLs adapted here are pBTTz and pBTT. Te is evaporated as an about 0.5 nm-thick discontinuous interlayer to increase the adhesion of Se films and serves as nucleation site for the t-Se.…”

“…It is clear that the performance of SSCs has been improved after a week, and the reason could be the strain releasing of Se polycrystalline films. [19,30] Ito et al reported that the efficiency of SSCs could keep increasing for 40 days due to releasing strains. [19] Todorov et al reported the fabricated SSCs could maintain the performance for more than half a year.…”

“…[27][28][29] The advantages of P3HT include good solubility in solvents such as dichlorobenzene (DCB), compact and uniform film morphology, and good stability. [30] The widely used electron transport layers (ETLs) are metal oxides such as TiO 2 and SnO 2 with high thermal stability. [16,30] However, these metal oxide films would decompose under an aqueous environment.…”

“…[30] The widely used electron transport layers (ETLs) are metal oxides such as TiO 2 and SnO 2 with high thermal stability. [16,30] However, these metal oxide films would decompose under an aqueous environment. For example, SnO 2 colloid precursor prepared by diluting SnO 2 particles into the aqueous solution and the morphology of SnO 2 film may be damaged by water diffusion.…”