Avci Can Onur, Rosenberg Ethan, Caretta Lucas, Büttner Felix, Mann Maxwell, Marcus Colin, Bono David, Ross Caroline A, Beach Geoffrey S D
Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
Nat Nanotechnol. 2019 Jun;14(6):561-566. doi: 10.1038/s41565-019-0421-2. Epub 2019 Apr 1.
Magnetic oxides exhibit rich fundamental physics and technologically desirable properties for spin-based memory, logic and signal transmission. Recently, spin-orbit-induced spin transport phenomena have been realized in insulating magnetic oxides by using proximate heavy metal layers such as platinum. In their metallic ferromagnet counterparts, such interfaces also give rise to a Dzyaloshinskii-Moriya interaction that can stabilize homochiral domain walls and skyrmions with efficient current-driven dynamics. However, chiral magnetism in centrosymmetric oxides has not yet been observed. Here we discover chiral magnetism that allows for pure spin-current-driven domain wall motion in the most ubiquitous class of magnetic oxides, ferrimagnetic iron garnets. We show that epitaxial rare-earth iron garnet films with perpendicular magnetic anisotropy exhibit homochiral Néel domain walls that can be propelled faster than 800 m s by spin current from an adjacent platinum layer. We find that, despite the relatively small interfacial Dzyaloshinskii-Moriya interaction, very high velocities can be attained due to the antiferromagnetic spin dynamics associated with ferrimagnetic order.
磁性氧化物展现出丰富的基础物理学特性以及在基于自旋的存储器、逻辑和信号传输方面技术上所需的特性。最近，通过使用诸如铂等邻近重金属层，在绝缘磁性氧化物中实现了自旋轨道诱导的自旋输运现象。在它们的金属铁磁对应物中，此类界面还会产生一种Dzyaloshinskii-Moriya相互作用，该相互作用能够通过高效的电流驱动动力学来稳定同手性畴壁和斯格明子。然而，在中心对称氧化物中尚未观察到手性磁性。在此，我们发现了手性磁性，它使得在最常见的一类磁性氧化物——亚铁磁性铁石榴石中实现纯自旋电流驱动的畴壁运动。我们表明，具有垂直磁各向异性的外延稀土铁石榴石薄膜展现出同手性奈尔畴壁，该畴壁能够被来自相邻铂层的自旋电流以超过800米每秒的速度推动。我们发现，尽管界面Dzyaloshinskii-Moriya相互作用相对较小，但由于与亚铁磁序相关的反铁磁自旋动力学，仍可实现非常高的速度。
