Beijing National Laboratory for Condensed Matter Physics & Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , People's Republic of China.
School of Physics , University of the Chinese Academy of Sciences , Beijing 100049 , People's Republic of China.
Nano Lett. 2019 Mar 13;19(3):1605-1612. doi: 10.1021/acs.nanolett.8b04509. Epub 2019 Feb 11.
With the help of the two-dimensional electron gas (2DEG) at the LaAlO-SrTiO interface, spin and charge currents can be interconverted. However, the conversion efficiency has been strongly depressed by LaAlO, which blocks spin transmission. It is therefore highly desired to explore 2DEGs sandwiched between ferromagnetic insulators that are transparent for magnons. By constructing epitaxial heterostructure with ferromagnetic EuO, which is conducting for spin current but insulating for electric current, and KTaO, we successfully obtained the 2DEGs, which can receive thermally injected spin current directly from EuO and convert the spin current to charge current via inverse Edelstein effect of the interface. Strong dependence of the spin Seebeck coefficient on the layer thickness of EuO is further observed and the propagation length for non-equilibrium magnons in EuO has been determined. The present work demonstrates the great potential of the 2DEGs formed by ferromagnetic oxides for spin caloritronics.
在 LaAlO-SrTiO 界面的二维电子气（2DEG）的帮助下，可以实现自旋和电荷流的相互转换。然而，LaAlO 强烈抑制了自旋输运，从而大大降低了转换效率。因此，人们非常希望探索夹在对于磁振子透明的铁磁绝缘体之间的 2DEG。通过构建具有铁磁 EuO 的外延异质结构，EuO 对自旋流是导电的，对电流是绝缘的，而 KTaO 是绝缘的，我们成功地获得了 2DEG，它们可以直接从 EuO 接收热注入的自旋流，并通过界面的逆 Edlestein 效应将自旋流转换为电荷流。进一步观察到自旋 Seebeck 系数对 EuO 层厚度的强烈依赖关系，并确定了 EuO 中非平衡磁振子的传播长度。本工作证明了由铁磁氧化物形成的 2DEG 在自旋卡尔替诺学中的巨大潜力。
