Transition metal dichalcogenide(TMDC)monolayers provide an ideal platform for exciton and valley-spintronics exploration due to their unique properties.Integrating TMDC monolayers with conventional semiconductors allo...Transition metal dichalcogenide(TMDC)monolayers provide an ideal platform for exciton and valley-spintronics exploration due to their unique properties.Integrating TMDC monolayers with conventional semiconductors allows for harnessing the unique properties of both materials.This strategy holds great promise for the development of advanced optoelectronics and spintronic devices.In this work,we investigated exciton and valley dynamics in WSe_(2)/Ga As heterostructure by employing the femtosecond pump-probe ultrafast spectroscopy.Facilitated by the charge transfer within the heterostructure,it was found that the exciton of WSe_(2)exhibited much longer lifetime of nanosecond than that of the WSe_(2)monolayer counterpart.Especially,a significantly long valley lifetime up to~2.7 ns was observed for trions of WSe_(2)in the heterostructure even under the off-resonant excitation,which is found to be associated with the resident electrons accumulated at the interface resulting from the charge transfer and resultant interfacial electric field.Our results provide fundamental references for conventional semiconductor-integrated TMDC heterostructures that have great potential for designing novel optoelectronic and spintronic devices.展开更多
Mn基二元合金L1_(0)-MnAl具有垂直磁各向异性强、自旋极化率高和磁阻尼因子低等特点,是研制高密度、高性能和低功耗磁随机存储器(magnetic random access memory,MRAM)的重要材料体系,而B2-CoGa合金则同时为外延生长在主流半导体GaAs上...Mn基二元合金L1_(0)-MnAl具有垂直磁各向异性强、自旋极化率高和磁阻尼因子低等特点,是研制高密度、高性能和低功耗磁随机存储器(magnetic random access memory,MRAM)的重要材料体系,而B2-CoGa合金则同时为外延生长在主流半导体GaAs上垂直磁各向异性L1_(0)-MnAl薄膜提供了理想的缓冲层和自旋流来源.本文报道了在B2-CoGa缓冲层中掺杂重金属Pt可以显著提高L1_(0)-MnAl/(CoGa)_(1-x)Pt_(x)双层膜中的自旋轨道矩(spin-orbit torque,SOT)效率.该双层膜在高达x=0.1的掺杂范围内仍然保持着良好的垂直磁各向异性,其磁矩实现翻转的临界电流密度可从4.63×10^(7)A/cm^(2)降低到2.59×10^(7)A/cm^(2),同时SOT效率从0.042提高到0.080.这种增强归因于在保持(CoGa)_(1-x)Pt_(x)有效自旋霍尔电导率不变的情况下其电阻率的增加.其中,x=0.075样品能够支持横向尺寸8.09 nm的磁性隧道结单元,同时功耗可降低至原来的0.63.这些结果为基于Mn基二元合金的MRAM研发提供了参考.展开更多
基金funded by the National Key Research and Development Program of China(Grant No.2022YFA1405100)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB43000000)。
文摘Transition metal dichalcogenide(TMDC)monolayers provide an ideal platform for exciton and valley-spintronics exploration due to their unique properties.Integrating TMDC monolayers with conventional semiconductors allows for harnessing the unique properties of both materials.This strategy holds great promise for the development of advanced optoelectronics and spintronic devices.In this work,we investigated exciton and valley dynamics in WSe_(2)/Ga As heterostructure by employing the femtosecond pump-probe ultrafast spectroscopy.Facilitated by the charge transfer within the heterostructure,it was found that the exciton of WSe_(2)exhibited much longer lifetime of nanosecond than that of the WSe_(2)monolayer counterpart.Especially,a significantly long valley lifetime up to~2.7 ns was observed for trions of WSe_(2)in the heterostructure even under the off-resonant excitation,which is found to be associated with the resident electrons accumulated at the interface resulting from the charge transfer and resultant interfacial electric field.Our results provide fundamental references for conventional semiconductor-integrated TMDC heterostructures that have great potential for designing novel optoelectronic and spintronic devices.
