2D Functional Minerals as Sustainable Materials for Magneto‐Optics

Abstract

chemical properties, 2D materials have long been the forefront of fundamental research and applications in optics and many other fields. [1][2][3][4] For instance, many efforts have been devoted to explore physical paradigms under 2D limit and enable novel optical devices, such as exciton-resonance-enabled lens, [5,6] wideband tunable mode lockers, [7,8] as well as photodetectors and harmonic generators in terahertz regime. [2,9] Noteworthy, together with recently reported 2D ferromagnets, [10][11][12] 2D materials based magneto-optics have attracted great attentions nowadays. Categorized by the interaction between material and incident light under magnetic field, four main magnetooptical effects are investigated commonly, namely the Zeeman effect, Faraday effect, magneto-optical Kerr effect, and Cotton-Mouton effect, in which 2D materials are recognized as promising matters. [13] Among these four magneto-optical effects, the Cotton-Mouton effect is of great benefits for transmitted light modulation in a see-through manner, with the potential applications ranging from sub-micron-scale dynamic light modulators to meter-scale displayable windows in future society. [14,15] The current electro-optical technologies based on liquid crystals face Liquid crystal devices using organic molecules are nowadays widely used to modulate transmitted light, but this technology still suffers from relatively weak response, high cost, toxicity and environmental concerns, and cannot fully meet the demand of future sustainable society. Here, an alternative approach to color-tunable optical devices, which is based on sustainable inorganic liquid crystals derived from 2D mineral materials abundant in nature, is described. The prototypical 2D mineral of vermiculite is massively produced by a green method, possessing size-to-thickness aspect ratios of >10 3 , inplane magnetization of >10 emu g −1 , and an optical bandgap of >3 eV. These characteristics endow 2D vermiculite with sensitive magneto-birefringence response, been several orders of magnitude larger than organic counterparts, as well as capability of broad-spectrum modulation. The finding consequently permits the fabrication of various magnetochromic or mechanochromic devices with low or even zero-energy consumption during operation. This work creates opportunities for the application of sustainable materials in advanced optics.

Salt‐Assisted Low‐Temperature Growth of 2D Bi2O2Se with Controlled Thickness for Electronics

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] In the past few years, 2D materials have been employed for the state-of-the-art electronic and optoelectronic devices. [14][15][16][17][18] Among the broad list of reported 2D materials, graphene is the most-prominent material due to its remarkably high carrier mobility. [19] However, the on/off switching in graphenebased field-effect transistors (FETs) is immensely difficult due to its zerobandgap.…”

Switchable and Reversible p+/n+ Doping in 2D Semiconductors by Ionic 2D Minerals

“…[46] Hence, the asymmetrically-distributed ions in ionic mica can be viewed as an electrostatic gate to dope the underneath 2D BP. In addition, such 2D mineral materials are found to be stable with clean surface at ultrathin thickness, [47] and can be produced in large quantities by using scalable top-down exfoliation techniques. [48,49] The RRAM switching behaviors in ionic mica verify the electrical controllable migration of ions in ionic mica (Figure 1c).…”

Recent advances in 2D organic−inorganic heterostructures for electronics and optoelectronics

“…They are single-layer materials exfoliated chemically or mechanically from their bulk part due to weak intermolecular forces present in stacked layers. 1,8,15,[56][57][58][59][60][61][62] The strong in-plane covalent bonding offers extraordinary mechanical strength while weak out-of-plane forces among stacked layers help to extract a single layer called 2D materials from their bulk counterparts. Depending on the composition, they can have a single-element plane like graphene and h-BN or multiatomic plane like MoS 2 with three atomic layers.…”

“…2D inorganic materials are considered attractive for researchers due to their unique electronic, optoelectronic, and bandgap tunability, covering the broadband spectrum with various materials, semimetal, semiconductors, and insulators. They are single‐layer materials exfoliated chemically or mechanically from their bulk part due to weak intermolecular forces present in stacked layers 1,8,15,56–62 . The strong in‐plane covalent bonding offers extraordinary mechanical strength while weak out‐of‐plane forces among stacked layers help to extract a single layer called 2D materials from their bulk counterparts.…”