Intrinsic ferromagnetism with high temperature, strong anisotropy and controllable magnetization in the CrX (X = P, As) monolayer.

2D ferromagnetic (FM) materials with high temperature, large magnetocrystalline anisotropic energy (MAE), and controllable magnetization are highly desirable for novel nanoscale spintronic applications. Herein by using DFT and Monte Carlo simulations, we demonstrate the possibility of realizing intrinsic ferromagnetism in 2D monolayer CrX (X = P, As), which are stable and can be exfoliated from their bulk phase with a van der Waals layered structure. Following the Goodenough-Kanamori-Anderson (GKA) rule, the long-range ferromagnetism of CrX is caused via a 90° superexchange interaction along Cr-P(As)-Cr bonds. The Curie temperature of CrP is predicted to be 232 K based on a Heisenberg Hamiltonian model, while the Berezinskii-Kosterlitz-Thouless transition temperature of CrAs is as high as 855 K. In contrast to other 2D magnetic materials, the CrP monolayer exhibits a significant uniaxial MAE of 217 µeV per Cr atom originating from spin-orbit coupling. Analysis of MAE reveals that CrP favors easy out-of-plane magnetization, while CrAs prefers easy in-plane magnetization. Remarkably, hole and electron doping can switch the magnetization axis in between the in-plane and out-of-plane direction, allowing for the effective control of spin injection/detection in 2D structures. Our results offer an ideal platform for realizing 2D magnetoelectric devices such as spin-FETs in spintronics.

Discovery of a ferroelastic topological insulator in a two-dimensional tetragonal lattice.

Ferroelasticity and band topology are two intriguing yet distinct quantum states of condensed matter materials. Their coexistence in a single two-dimensional (2D) lattice, however, has never been observed. Here, we found that the 2D tetragonal HfC monolayer allowed simultaneous presence of ferroelastic and topological orders. By using first-principles calculations, we found that it could allow a low switching barrier with reversible strain of 17.4%, indicating that the anisotropic properties are achievable experimentally for a 2D tetragonal lattice. More interestingly, the tuning of topological behaviors with strain led to spin-separated and gapless edge states, that is, the quantum spin Hall effect. These findings from the coupling of two quantum orders offer insights into ferroelastic control over topological edge states for achieving multifunctional properties in next-generation 2D nanodevices.

[Luring effect of the fermented Laminaria japonica to Oncomelania hupensis].

OBJECTIVE: To study the attraction effect of the food attractants on Oncomelania hupensis. METHODS: Oncomelania snail food was prepared with the fermented kelp (Laminaria japonica) mixed with corn starch. Snails were fed with the food and kept for 12, 24, 36, and 48 h at 15, 25, 35 degrees C respectively. Meanwhile, snail-killing effect was tested by granules containing jack-in-the-pulpit (Arisama heterophyllum) with or without the fermented kelp under the condition of 25 degrees C, 30% or 60% soil humidity. RESULTS: The snail-attracting rate of the fermented kelp was affected by the temperature, highest under 25 degrees C and lowest under 35 degrees C at any time point, with a rate of 80.3% in 48 h at 25 degrees C which was higher than that of the control (17.0%) (P<0.01). The snail mortality rate in the group using jack-in-the-pulpit with fermented kelp (85.3%) was higher than that of the group without fermented kelp (26.8%) (P<0.05). The mortality under 60% of soil humidity was higher than that under 30% humidity (P<0.01). CONCLUSION: The fermented kelp shows a strong luring effect to the Oncomelania snails.

[Preliminary study on molluscicidal effect of active components from Centipeda minima].

The active components from Centipeda minima were extracted by water or ethanol, and identified by FTIR spectroscopy and UV-visible spectrophotometer. The molluscicidal effect of aqueous extract and ethanol extract from Centipeda minima against Oncomelania hupensis was determined as referring to the WHO guidelines for laboratory molluscicidal test. Treated with over 2.0 g/L aqueous extract and ethanol extract for five days, the mortality of O. hupensis was up to 100%, and their LC50, for snails was 0.50 g/L and 0.62 g/L, respectively. The molluscicidal activity of aqueous extract was higher than that of ethanol extract. The main components of aqueous extract and ethanol extract were sesquiterpenes lactones and sterols.