Nat Mater. 2011 Jun 26;10(9):655-9. doi: 10.1038/nmat3052.
Injection of spin currents into solids is crucial for exploring spin physics and spintronics. There has been significant progress in recent years in spin injection into high-resistivity materials, for example, semiconductors and organic materials, which uses tunnel barriers to circumvent the impedance mismatch problem; the impedance mismatch between ferromagnetic metals and high-resistivity materials drastically limits the spin-injection efficiency. However, because of this problem, there is no route for spin injection into these materials through low-resistivity interfaces, that is, Ohmic contacts, even though this promises an easy and versatile pathway for spin injection without the need for growing high-quality tunnel barriers. Here we show experimental evidence that spin pumping enables spin injection free from this condition; room-temperature spin injection into GaAs from Ni(81)Fe(19) through an Ohmic contact is demonstrated through dynamical spin exchange. Furthermore, we demonstrate that this exchange can be controlled electrically by applying a bias voltage across a Ni(81)Fe(19)/GaAs interface, enabling electric tuning of the spin-pumping efficiency.
向固体中注入自旋电流对于探索自旋物理和自旋电子学至关重要。近年来，在向高阻材料（例如半导体和有机材料）中注入自旋方面取得了重大进展，其中利用隧道势垒来规避阻抗失配问题；铁磁金属与高阻材料之间的阻抗失配极大地限制了自旋注入效率。但是，由于这个问题，即使通过低阻界面（即欧姆接触）向这些材料中注入自旋也没有途径，尽管这为自旋注入提供了一种简单而通用的方法，而无需生长高质量的隧道势垒。在这里，我们通过动态自旋交换实验证明了自旋泵浦可以使自旋注入摆脱这种条件；通过动态自旋交换，从 Ni(81)Fe(19)通过欧姆接触向 GaAs 中实现了室温自旋注入。此外，我们证明可以通过在 Ni(81)Fe(19)/GaAs 界面上施加偏置电压来控制这种交换，从而实现对自旋泵浦效率的电调谐。
