Laboratory of Atomic and Solid-State Physics, Cornell University, Ithaca, NY, 14853, USA.
Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.
Nat Commun. 2023 Apr 26;14(1):2393. doi: 10.1038/s41467-023-38095-3.
We present room-temperature measurements of magnon spin diffusion in epitaxial ferrimagnetic insulator MgAlFeO (MAFO) thin films near zero applied magnetic field where the sample forms a multi-domain state. Due to a weak uniaxial magnetic anisotropy, the domains are separated primarily by 180° domain walls. We find, surprisingly, that the presence of the domain walls has very little effect on the spin diffusion - nonlocal spin transport signals in the multi-domain state retain at least 95% of the maximum signal strength measured for the spatially-uniform magnetic state, over distances at least five times the typical domain size. This result is in conflict with simple models of interactions between magnons and static domain walls, which predict that the spin polarization carried by the magnons reverses upon passage through a 180° domain wall.
我们展示了在零外磁场下外延铁磁共振各向异性绝缘体 MgAlFeO（MAFO）薄膜中磁振子自旋扩散的室温测量结果，此时样品呈现多畴状态。由于弱的单轴各向异性，畴主要由 180°畴壁隔开。令人惊讶的是，我们发现畴壁的存在对自旋扩散的影响很小——在多畴状态下的非局域自旋输运信号至少保留了在空间均匀磁态下测量到的最大信号强度的 95%，在距离至少是典型畴尺寸五倍的范围内。这一结果与磁振子与静态畴壁相互作用的简单模型相矛盾，该模型预测磁振子携带的自旋极化在穿过 180°畴壁时会反转。
