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Science Advances reports ICQM faculty member Wei Han group’s work on the inverse Edelstein effect in the Rashba-split 2DEG between SrTiO3 and LaAlO3 at room temperature
《Science Advances》刊登量子材料中心韩伟课题组关于全氧化物界面Rashba二维电子气中自旋和电荷转换的研究工作

Recently, Wei Han’s group, from the International Center for Quantum Materials (ICQM), demonstrated the spin injection and observation of inverse Edelstein effect in the Rashba-split 2DEG between SrTiO3 and LaAlO3 at room temperature. This work is cooperated with Jirong Sun’s group from institute of physics, Chinese academy of science. That is the first time to observe the inverse Edelstein effect generated spin signal in the 2DEG between two insulating oxides SrTiO3 and LaAlO3 up to room temperature. The work was reported by Science Advances with the title of “Observation of Inverse Edelstein Effect in Rashba-Split 2DEG between SrTiO3 and LaAlO3 at Room Temperature ”.

In 1990, Edelstein predicted that spin current could be induced by charge current flowing in inversion asymmetric two-dimensional electron gases (2DEGs), which is often referred to as the Edelstein effect (EE). The magnitude of EE highly depends on the Rashba spin-orbit coupling, which provides a locking between the momentum and spin polarization directions, as illustrated in fig (a). The opposite of EE is often called inverse Edelstein effect (IEE), which means that spin accumulation in inversion asymmetric 2DEG could generate an in-plane electric field perpendicular to the spin polarization direction. Because of the potential highly efficient spin-and-charge conversion, both the EE and IEE have attracted a great deal of interest for spintronics, and various experiments have been performed on the Rashba interfaces between two metallic films, two-dimensional materials, and the topological surface states.

Figure. Observation of inverse Edelstein effect (IEE) in Rashba-split 2DEG between SrTiO3 and LaAlO3 at room temperature. A, The energy dispersion for a typical Rashba spin-split 2DEG. B, Schematic drawing of the IEE measurements. C. The gate voltage dependence of IEE of the Rashba-split 2DEG between 3 UC LaAlO3 and SrTiO3 at room temperature. Credit: International Center for Quantum Materials, Peking University.

With the high-quality LAO/STO samples provided by the group of Jirong Sun, Wei Han’s group uses the spin pumping technique to inject the spin current from Py electrode through a LaAlO3 layer with a thickness of up to 40 unit cells into the 2DEG at the junction interface and measured the inverse Edelstein effect at the room temperature, as illustrated in the figure (b). Systematical measurements, including frequency, power, temperature and LAO thickness dependences of the spin signal strongly support the observation. As shown in figure(c), The gate voltage dependence of the spin signal indicate the gate voltage a powerful tool to turn the spin-to-charge conversion efficiency and even to turn the signal on/off.

This work has been published on Science Advances on March 17, 2017 (Science Advances, 3, e1602312 (2017)). PhD student Qi Song from ICQM and Hongrui Zhang from IOP are the co-first authors of this paper. This work was supported by National Basic Research Programs of China, National Natural Science Foundation of China, the Strategic Priority Research Program of the Chinese Academy of Sciences, Recruitment Program of Global Experts, CAS Hundred Talent Program, the DOE BES Award, the support by the 1000 Talents Program for Young Scientists of China.

Besides, it is worth to mention that the France team led by Prof. Fert, 2007 Nobel Laureate in physics, also did a work on the spin and charge conversion at the oxide interface. Their work is published in Nature Materials (Nature Materials 15, 1261–1266 (2016)), which is a little earlier than the work discussed above.

Both these two work reveal that the oxide interface could be used for spintronics devices, such as efficient charge-to-spin conversion for the generation and detection of spin current.



Link to the Science Advances paper:

Link to the Nature Materials paper by the France team led by Prof. Fert (2007 Nobel Laureate): http://www.nature.com/nmat/journal/v15/n12/full/nmat4726.html

Link to Prof. Wei Han’s group page: http://www.phy.pku.edu.cn/~LabSpin/home.html

  近日, 北京大学量子材料科学中心韩伟课题组与中科院物理所孙继荣课题组共同合作,对Rashba自旋分裂的二维电子气进行了自旋注入和自旋电荷转换的研究,并在室温成功的发现逆Edelstein效应产生的自旋信号。该工作被《Science Advances》杂志以标题“Observation of Inverse Edelstein Effect in Rashba-Split 2DEG between SrTiO3 and LaAlO3 at Room Temperature”报道。



图: 在SrTiO3/LaAlO3异质结界面处Rashba二维电子气中观测到逆 Edelstein效应。A,Rashba自旋分裂的二维电子气的色散关系。B,逆 Edelstein效应测量示意图。C,室温下使用门电压调控SrTiO3/3UC LaAlO3界面处Rashba二维电子气中的逆Edelstein效应信号

  相关文章已于2017年03月17日在Science Advances上在线刊登(Science Advances, 3, e1602312 (2017))。北大博士生宋琪和物理所博士生张洪瑞为共同第一作者,该项工作得到了国家自然科学基金委、国家科技部、中科院、中科院百人计划以及中组部千人计划的经费支持。

  另外,特别值得一提的是,诺贝尔奖得主法国Fert教授团队也对SrTiO3/LaAlO3界面的自旋和电荷转换进行了研究,他们的文章比韩伟课题组及其合作者的工作略早在Nature Materials上发表(Nature Materials 15, 1261–1266 (2016))。



论文链接: http://advances.sciencemag.org/content/3/3/e1602312





韩伟研究员实验室主页: http://www.phy.pku.edu.cn/~LabSpin/home.html