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arXiv 2211.03383cond-mat.mtrl-sci
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室温下基于SrTiO3界面的准二维电子气中的电荷-自旋转换

Room temperature charge-to-spin conversion from q-2DEG at SrTiO3-based interfaces

Utkarsh Shashank, Angshuman Deka, Chen Ye, Surbhi Gupta, Rohit Medwal, Rajdeep Singh Rawat, Hironori Asada, X. Renshaw Wang, Yasuhiro Fukuma

AI总结:

本研究通过SrTiO3/AlN和SrTiO3/Al2O3界面,提出机制并开发分析方案,估算电荷-自旋转换效率,发现氧空位贡献显著,结果与晶态相当,为缺陷工程增强转换提供途径。

摘要:

界面二维电子气(2DEG),尤其是出现在绝缘体意外界面上的SrTiO3基二维电子气,已成为高效电荷-自旋电流相互转换的有前景候选材料。本文为深入理解氧化物基二维电子气中电荷-自旋电流相互转换的机制,聚焦于绝缘SrTiO3与两种铝基非晶绝缘体(即SrTiO3/AlN和SrTiO3/Al2O3)之间的导电界面,并估算了其电荷-自旋转换效率θ_cs。选择这两种非晶绝缘体是为了明确探测氧空位对θ_cs的常被忽视的贡献。我们提出了一种机制来解释自旋力矩铁磁共振(ST-FMR)测量的结果,并开发了一种分析方案以可靠估算氧化物基二维电子气的θ_cs。由此得到的θ_cs/t(其中t为二维电子气厚度)对SrTiO3/AlN和SrTiO3/Al2O3分别估计为0.244 nm⁻¹和0.101 nm⁻¹,且与它们的晶态对应物惊人地相当。此外,我们还观察到SrTiO3/AlN样品中谐振线宽的大幅直流调制,证实了其高θ_cs,并证明了氧空位使能的电荷-自旋转换。我们的发现强调了缺陷对电荷-自旋相互转换的贡献,尤其是在氧化物基低维系统中,并提供了一种通过缺陷工程创造和增强电荷-自旋相互转换的途径。

英文摘要:

Interfacial two-dimensional electron gas (2DEG), especially the SrTiO3-based ones at the unexpected interface of insulators, have emerged to be a promising candidate for efficient charge-spin current interconversion. In this article, to gain insight into the mechanism of the charge-spin current interconversion at the oxide-based 2DEG, we focused on conducting interfaces between insulating SrTiO3 and two types of aluminium-based amorphous insulators, namely SrTiO3/AlN and SrTiO3/Al2O3, and estimated their charge-spin conversion efficiency, θ_cs. The two types of amorphous insulators were selected to explicitly probe the overlooked contribution of oxygen vacancy to the θ_cs. We proposed a mechanism to explain results of spin-torque ferromagnetic resonance (ST-FMR) measurements and developed an analysis protocol to reliably estimate the θ_cs of the oxide based 2DEG. The resultant θ_cs/t, where t is the thickness of the 2DEG, were estimated to be 0.244 nm-1 and 0.101 nm-1 for the SrTiO3/AlN and SrTiO3/Al2O3, respectively, and they are strikingly comparable to their crystalline counterparts. Furthermore, we also observe a large direct current modulation of resonance linewidth in SrTiO3/AlN samples, confirming its high θ_cs and attesting an oxygen-vacancy-enabled charge-spin conversion. Our findings emphasize the defects' contribution to the charge-spin interconversion, especially in the oxide-based low dimensional systems, and provide a way to create and enhance charge-spin interconversion via defect engineering.

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