Liang Hu,Jian Zhou,Zhipeng Hou,Weitao Su,Bingzhang Yang,Lingwei Li,Mi Yan
The demand for high-performance spintronic devices has boosted intense research on the manipulation of magnetism in van der Waals (vdW) magnets. Despite great efforts, robust ferromagnetic transitions above room temperature still face significant hurdles. Strain engineering can reversibly regulate magnetic exchange, but the degree of regulation is still impractical for most magnetic applications. Hereby we employ a large-strain transferrer to produce tunable strains of up to 4.7%, which induces authentic room-temperature ferromagnetism in large-area Fe3GeTe2 nanoflakes with 20-fold improvement in magnetization. The record increment of the Curie temperature (TC) of well above 400 K originates from the strain-enhanced magnetic anisotropy and excellent magnetoelastic coupling. The correlation between the emerging ferromagnetism and Raman spectral evolution is also established, which complements well the TC phase diagram in a large-strain region. In addition, an unusual exchange bias effect with a vertical magnetization shift is tracked for the first time upon bending, which reveals the hidden competition between antiferromagnetic and ferromagnetic coupling. The reversible strain manipulation of single-domain ferromagnetic order in a single nanoflake further opens up a route to develop low-power wearable spintronic devices. The findings here provide vast opportunities to exploit the possibility of practical applications of more vdW magnets.
Jie Wang,Changzhou Gao,Jiaojiao Fang,Liang Fang,Chunhua Lu,Zhongzi Xu
Light and heat management in greenhouses are important for crops yield and quality. Here, we created waterborne polyurethane (WPU) composite coatings for greenhouse films, which can act both as ultraviolet (UV) light down-conversion and directional infrared light barrier for the light and temperature conditions in pepper greenhouses. Rare-earth organic complexes (REOC) that can convert UV light to red light were mixed with WPU by ball-milling. The REOC nanoparticles presented good dispersion in WPU coatings, which were determined by atomic force microscopy , and the coating with 1 wt% REOC still remained comparably high transparency. The luminescence properties were increased with REOC loadings. The coatings with REOC showed lower infrared (IR) light transmittance and higher IR light reflectance than those of the pristine film and WPU coatings. The preferable location of the composite coatings on inner side of films acted as IR light barrier and facilitated the maintenance of heat inside the greenhouses, increasing the temperature. Simulation was performed to testify the temperature increase using IR barrier covered layer. Small and big greenhouses with different films were built and the temperatures were recorded. The results show that the film containing REOC increase the temperature in the greenhouses by >2 °C compared to traditional agricultural films. Finally, due to light conversion and IR light barrier, the yields of green peppers can be increased by 35 %. The mass of single fruits can also be increased by 8 g.
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