Chan Chun-Wen, Hsieh Chia-Yun, Chan Fang-Mei, Huang Pin-Jia, Yang Chao-Yao
Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu 300093, Taiwan.
Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu 300093, Taiwan.
Materials (Basel). 2024 Aug 8;17(16):3933. doi: 10.3390/ma17163933.
Transition metal dichalcogenide (TMD) monolayers exhibit unique valleytronics properties due to the dependency of the coupled valley and spin state at the hexagonal corner of the first Brillouin zone. Precisely controlling valley spin-polarization via manipulating the electron population enables its application in valley-based memory or quantum technologies. This study uncovered the uncompensated spins of the antiferromagnetic nickel oxide (NiO) serving as the ferromagnetic (FM) order to induce valley spin-polarization in molybdenum disulfide (MoS) monolayers via the magnetic proximity effect (MPE). Spin-resolved photoluminescence spectroscopy (SR-PL) was employed to observe MoS, where the spin-polarized trions appear to be responsible for the MPE, leading to a valley magnetism. Results indicate that local FM order from the uncompensated surface of NiO could successfully induce significant valley spin-polarization in MoS with the depolarization temperature approximately at 100 K, which is relatively high compared to the related literature. This study reveals new perspectives in that the precise control over the surface orientation of AFMs serves as a crystallographic switch to activate the MPE and the magnetic sustainability of the trion state is responsible for the observed valley spin-polarization with the increasing temperature, which promotes the potential of AFM materials in the field of exchange-coupled Van der Waals heterostructures.
过渡金属二硫属化物（TMD）单层由于在第一布里渊区六角角上耦合谷和自旋态的依赖性而表现出独特的谷电子学特性。通过操纵电子数量精确控制谷自旋极化，使其能够应用于基于谷的存储器或量子技术。本研究发现反铁磁氧化镍（NiO）的未补偿自旋作为铁磁（FM）序，通过磁近邻效应（MPE）在二硫化钼（MoS）单层中诱导谷自旋极化。采用自旋分辨光致发光光谱（SR-PL）来观察MoS，其中自旋极化的三重激子似乎是MPE的原因，导致谷磁性。结果表明，来自NiO未补偿表面的局部FM序能够成功地在MoS中诱导出显著的谷自旋极化，去极化温度约为100 K，与相关文献相比相对较高。这项研究揭示了新的观点，即对反铁磁体表面取向的精确控制作为激活MPE的晶体学开关，并且三重激子态的磁可持续性是观察到的随温度升高的谷自旋极化的原因，这促进了反铁磁材料在交换耦合范德华异质结构领域的潜力。
