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Unexpected Photoinduced Room Temperature Magnetization in Bi2WO6 Nanosheets
Small ( IF 13.0 ) Pub Date : 2020-11-23 , DOI: 10.1002/smll.202005704
Jing Wei 1 , Yuguo Xia 1 , Abdul Qayum 1 , Xiuling Jiao 1 , Dairong Chen 1 , Ting Wang 1
Small ( IF 13.0 ) Pub Date : 2020-11-23 , DOI: 10.1002/smll.202005704
Jing Wei 1 , Yuguo Xia 1 , Abdul Qayum 1 , Xiuling Jiao 1 , Dairong Chen 1 , Ting Wang 1
Affiliation
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The current investigation in magnetism in 2D materials offers new opportunities for studying spintronics at low dimensions. Here, reversible photoinduced room temperature magnetization in 2D Bi2WO6 nanosheets is reported for the first time. Compared with the original state, the ultraviolet (UV)‐illuminated Bi2WO6 nanosheets show a yellow‐green color change and significantly enhanced magnetic signals (saturated magnetization (Ms) increased from 0.002 to 0.12 emu g−1). X‐ray photoelectron spectroscopy (XPS) results show unexpected W reduction (W6+ to W5+/W4+) and Bi oxidation (Bi3+ to Bi5+) upon UV illumination for the Bi2WO6 nanosheets, indicating a photoexcited Bi to W charge transfer. Density functional theory (DFT) calculations indicate spontaneous spin polarization of the Bi2WO6 nanosheets in the excited metastable state. Meanwhile, thicker Bi2WO6 nanoplates or nanoparticles show no enhanced magnetic signals upon UV illumination. UV illumination of the thin Bi2WO6 nanosheets can induce the formation of internal electric field (polarization), leading to structural deformation/lattice distortion (photostriction). The photoexcited electrons are trapped in the WO6 layers while the photogenerated holes are trapped in the Bi2O2 layers, leading to spin polarization and enhance the magnetization. The research may bring some new insights in tuning the magnetic properties of 2D nanostructures.
中文翻译：
Bi2WO6纳米片中意外的光致室温磁化强度。
当前在2D材料中磁性的研究为研究低尺寸自旋电子学提供了新的机会。在此，首次报道了二维Bi 2 WO 6纳米片中可逆的光诱导室温磁化强度。与原始状态相比，用紫外线（UV）照射的Bi 2 WO 6纳米片显示出黄绿色的变化，并且磁信号显着增强（饱和磁化强度（M s）从0.002 emu g -1增加）。X射线光电子能谱（XPS）结果显示出意外的W还原（W 6+至W 5+ / W4 +）和Bi氧化（Bi 3+至Bi5 +）的Bi 2 WO 6纳米片在紫外线照射下，表明光激发的Bi到W电荷转移。密度泛函理论（DFT）计算表明Bi 2 WO 6纳米片在激发的亚稳态下自发自旋极化。同时，更厚的Bi 2 WO 6纳米板或纳米颗粒在紫外线照射下没有显示出增强的磁信号。Bi 2 WO 6纳米薄片的紫外线照射会诱导内部电场的形成（极化），从而导致结构变形/晶格变形（光致伸缩）。光激发电子被捕获在WO 6中由于光生空穴被捕获在Bi 2 O 2层中，导致自旋极化并增强了磁化强度。该研究可能会在调整2D纳米结构的磁性方面带来一些新见解。
更新日期：2020-12-17
中文翻译：
Bi2WO6纳米片中意外的光致室温磁化强度。
当前在2D材料中磁性的研究为研究低尺寸自旋电子学提供了新的机会。在此，首次报道了二维Bi 2 WO 6纳米片中可逆的光诱导室温磁化强度。与原始状态相比，用紫外线（UV）照射的Bi 2 WO 6纳米片显示出黄绿色的变化，并且磁信号显着增强（饱和磁化强度（M s）从0.002 emu g -1增加）。X射线光电子能谱（XPS）结果显示出意外的W还原（W 6+至W 5+ / W4 +）和Bi氧化（Bi 3+至Bi5 +）的Bi 2 WO 6纳米片在紫外线照射下，表明光激发的Bi到W电荷转移。密度泛函理论（DFT）计算表明Bi 2 WO 6纳米片在激发的亚稳态下自发自旋极化。同时，更厚的Bi 2 WO 6纳米板或纳米颗粒在紫外线照射下没有显示出增强的磁信号。Bi 2 WO 6纳米薄片的紫外线照射会诱导内部电场的形成（极化），从而导致结构变形/晶格变形（光致伸缩）。光激发电子被捕获在WO 6中由于光生空穴被捕获在Bi 2 O 2层中，导致自旋极化并增强了磁化强度。该研究可能会在调整2D纳米结构的磁性方面带来一些新见解。
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