Lee Won-Yong, Kang Min-Sung, Kim Gil-Sung, Park No-Won, Choi Kwang-Yong, Le Chinh Tam, Rashid Mamoon Ur, Saitoh Eiji, Kim Yong Soo, Lee Sang-Kwon
Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea.
Department of Physics and Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 44610, Republic of Korea.
ACS Appl Mater Interfaces. 2021 Apr 7;13(13):15783-15790. doi: 10.1021/acsami.0c22345. Epub 2021 Mar 26.
The spin Seebeck effect (SSE) has attracted renewed interest as a promising phenomenon for energy harvesting systems. A noteworthy effort has been devoted to improving the SSE voltage by inserting ultrathin magnetic layers including FeCu interlayers in Pt/YFeO (Pt/YIG) systems with increased spin-mixing conductance at the interfaces. Nevertheless, the responsible underlying physics associated with the role of the interlayer in Pt/YIG systems in the SSE is still unknown. In this paper, we demonstrate that with a monolayer tungsten diselenide (ML WSe) interlayer in the Pt/YIG bilayer system, the longitudinal SSE (LSSE) voltage is significantly increased by the increased spin accumulation in the Pt layer; the spin fluctuation in ML WSe amplifies the spin current transmission because the in-plane-aligned WSe spins are coupled to thermally pumped spins under nonequilibrium magnetization conditions in the LSSE configuration at room temperature. The thermopower (/ΔT) improves by 323% with respect to the value of the reference Pt/YIG bilayer sample in the LSSE at room temperature. In addition, the induced ferromagnetic properties of the ML WSe flakes on YIG increase the LSSE voltage () of the sample; the ferromagnetic properties are a result of the improved magnetic moment density in the ML WSe flakes and their two-dimensional (2D) ML nature in the LSSE under nonequilibrium magnetization conditions. The results can extend the application range of the materials in energy harvesting and provide important information on the physics of the LSSE with a transition metal dichalcogenide intermediate layer in spin transport.
自旋塞贝克效应（SSE）作为能量收集系统中一种很有前景的现象，重新引起了人们的关注。人们致力于通过在Pt/YFeO（Pt/YIG）系统中插入包括FeCu中间层在内的超薄磁性层来提高SSE电压，这些中间层可增加界面处的自旋混合电导。然而，与Pt/YIG系统中中间层在SSE中的作用相关的潜在物理机制仍然未知。在本文中，我们证明，在Pt/YIG双层系统中插入单层二硒化钨（ML WSe）中间层时，Pt层中自旋积累的增加会显著提高纵向SSE（LSSE）电压；ML WSe中的自旋涨落会放大自旋电流传输，因为在室温下的LSSE配置中，在非平衡磁化条件下，面内排列的WSe自旋与热泵浦自旋耦合。在室温下的LSSE中，相对于参考Pt/YIG双层样品的值，热功率（/ΔT）提高了323%。此外，YIG上ML WSe薄片的诱导铁磁特性增加了样品的LSSE电压（）；铁磁特性是由于在非平衡磁化条件下，LSSE中ML WSe薄片的磁矩密度提高及其二维（2D）ML性质所致。这些结果可以扩展材料在能量收集中的应用范围，并为自旋输运中具有过渡金属二卤化物中间层的LSSE物理提供重要信息。
