Magnetic Electrides : High-Throughput Material Screening, Intriguing Properties, and Applications

Electrides are a unique class of electron-rich materials where excess electrons are localized in interstitial lattice sites as anions, leading to a range of unique properties and applications. While hundreds of electrides have been discovered in recent years, magnetic electrides have received limited attention, with few investigations into their fundamental physics and practical applications. In this work, 51 magnetic electrides (12 antiferromagnetic, 13 ferromagnetic, and 26 interstitial-magnetic) were identified using high-throughput computational screening methods and the latest Materials Project database. Based on their compositions, these magnetic electrides can be classified as magnetic semiconductors, metals, or half-metals, each with unique topological states and excellent catalytic performance for N2 fixation due to their low work functions and excess electrons. The novel properties of magnetic electrides suggest potential applications in spintronics, topological electronics, electron emission, and as high-performance catalysts. This work marks the beginning of a new era in the identification, investigation, and practical applications of magnetic electrides.</p

The moss genus Didymodon as an indicator of climate change on the Tibetan Plateau

Bryophytes are sensitive to changing atmospheric conditions. Potentially, typical alpine bryophytes are valuable indicators of climate change for alpine ecosystems. However, little is known about the effects of climate change on the dominant alpine bryophytes of the Tibetan Plateau. In this study, we compared suitable habitats and predicted the effects of key environmental variables, in three climate change scenarios (RCP 2.6, RCP 4.5 and RCP 8.5), on the distribution of two dominant moss genera, a typically alpine xerophytic functional group, Bryoerythrophyllum and Didymodon in Pottiaceae. We used Maximum Entropy model (MaxEnt) modelling, for the 2050s and 2070s in Tibet. Simulation-based estimates suggest that Bryoerythrophyllum are more suited to habitats from semi-humid regions to semi-arid regions while Didymodon are relatively drought-resistant mosses that mainly inhabit drought regions. The variables associated with temperature will have the strongest effect on the future distribution patterns of both Bryoerythrophyllum and Didymodon when compared with precipitation and topographic variables. However, Climate change should affect Didymodon the most, due to its relatively narrow temperature and precipitation range for optimum growth. Additionally, Bryoerythrophyllum is predicted with a ratio of increase in suitable areas at 19.08%, 141.49% and 121.56% and 55.22%, 129.93% and 172.08% under all three scenarios, for 2050 and 2070, respectively. In contrast, Didymodon has a ratio of increase in suitable areas at −25.36%, 12.51% and 51.1% and 13.71%, 14.27% and 131.91%, for all three scenarios for the two future decades, respectively. However, there are more obviously regular expansions and contractions can be easily caught for Didymodon than for Bryoerythrophyllum with GHG emissions from low to high. In summary, although Bryoerythrophyllum and Didymodon are evolutionarily closely related and have similar distribution patterns and future upward and northward shifts, Didymodon will respond more to climate warming under each climatic scenario for the 2050s and 2070s. Therefore, Didymodon is recommended as an indicator of climate change on the Tibetan Plateau

Controlled growth of atomically thin MoSe2 films and nanoribbons by chemical vapor deposition

Atomically thin transition metal dichalcogenides (TMDCs) have drawn much interest for their promising applications in electronic, optoelectronic, valleytronic and sensing fields. Controlled growth of large-scale and high-quality TMDC nanostructures is highly desirable but remains challenging. In the present work, large-scale monolayer, bilayer and few-layer MoSe2 films have been controllably synthesized by ambient pressure chemical vapor deposition (APCVD). Hydrogen flow rate, growth temperature as well as selenium–metal flux ratio have been systematically investigated, which were demonstrated to play a key role in the synthesis of MoSe2 nanostructures. We have also reported the successful growth of MoSe2 nanoribbons with controlled width and length on diverse substrates by APCVD with the assistance of sodium chloride and corresponding growth mechanism was proposed. Our findings highlight the prospects for the controlled growth of novel 1D and 2D TMDC nanostructures for nanoelectronic devices and the development of mixed-dimensional heterostructures

Multifold Fermions and Fermi Arcs Boosted Catalysis in Nanoporous Electride 12CaO·7Al2O3

Topological materials have been recently regarded as ideal catalysts for heterogeneous reactions due to their surface metallic states and high carrier mobility. However, the underlying relationship between their catalytic performance and topological states is under debate. It has been discovered that the electride 12CaO·7Al2O3 (C12A7:4e−) hosts multifold fermions and Fermi arcs on the (001) surface near the Fermi level due to the interstitial electrons. Through the comparison of catalytic performance under different doping and strain conditions, based on the hydrogen evolution process, it has been demonstrated that the excellent catalytic performance indeed originates from topological properties. A linear relationship between the length of Fermi arcs, and Gibbs free energy (ΔGH*) has been found, which not only provides the direct evidence to link the enhanced catalytic performance and surface Fermi arc states, but also fully clarifies the fundamental mechanism in topological catalysis.</p

Rapid thermal annealing study of magnetoresistance and perpendicular anisotropy in magnetic tunnel junctions based on MgO and CoFeB

The tunneling magnetoresistance and perpendicular magnetic anisotropy in CoFeB(1.1-1.2 nm)/MgO/CoFeB(1.2-1.7 nm) junctions were found to be very sensitively dependent on annealing time. During annealing at a given temperature, decay of magnetoresistance occurs much earlier compared to junctions with in-plane magnetic anisotropy. Through a rapid thermal annealing study, the decrease of magnetoresistance is found to be associated with the degradation of perpendicular anisotropy, instead of impurity diffusion as observed in common in-plane junctions. The origin of the evolution of perpendicular anisotropy as well as possible means to further enhance tunneling magnetoresistance is discussed

Corrigendum to 'Topological surface state: Universal catalytic descriptor in topological catalysis' [Mater. Today 67 (2023) 23–32, (S1369702123001384), (10.1016/j.mattod.2023.05.002)]

The authors regret the omission of the reference citation in the caption of Fig. 1a-b in the initially published version of this article. The inspiration for Fig. 1a-b in this article is drawn from Fig. 1a&amp;b of reference [40] of the article, authored by Li et al. and published in 2018 in Sci. China Mater. 61 (2018) 23–29. Building upon their work, we have further expanded our conceptual design, as depicted in Fig. 1c. Our findings demonstrate that nodal-net semimetals hold significant promise for possessing multiple active surfaces and exhibiting high catalytic performance. This is attributed to their possession of multiple nodal lines on distinct planes and drumhead surface states on various surfaces. The corrected version for the caption of FIG 1 follows below: Figure 1. Design scheme of topological catalysts based on the momentum space and surface density of states (DOSs) for Weyl semimetal, nodal line semimetal and nodal-net semimetal. (a) A pair of Weyl points in bulk and Fermi arcs on (001) and (010) surfaces. (b) Single nodal line in bulk and the drumhead surface states on (001) surface and arc-like states on (010) surface. (c) Nodal-nets in bulk and the drumhead surface states on (001) and (010) surfaces. The corresponding projected DOSs are displayed in right panels. It is important to note that the visual representation in (a) and (b) closely follows the concepts from Figure 1&amp;b in reference [40], with slight modifications. Inspired by reference [40], we have expanded our conceptual design to encompass nodal-net semimetals, as depicted in (c). The authors would like to apologise for any inconvenience caused.</p

Topological surface state: Universal catalytic descriptor in topological catalysis

Catalytic descriptors of electrocatalysts such as d-band center are the important indicators that connect the physiochemical interaction and catalytic performance and have been used for rational design of the catalysts and performance optimizations. However, these descriptors developed in traditional electrocatalysts are invalid in recent emerged topological catalysis. Here, we identify topological surface state (TSS) density at the Fermi level can serve as the universal catalytic descriptor in the family of metal diborides, the materials hosting fantasying topological nodal-net states. The catalytic activity for hydrogen evolution reaction (HER) is linearly correlated with the projected TSSs on corresponding surfaces, which are independent on the material types. The findings are further proven by the weakened HER performance under topological phase transition where the TSS density at Fermi level is reduced, and the revival of d-band center once all the TSSs are removed. Our work will open a new route for developing high-performance catalysts from the quantum topological point of view.</p