Birefringence-like spin transport via linearly polarized antiferromagnetic magnons
Birefringence-like spin transport via linearly polarized antiferromagnetic magnons
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DOI：
10.1038/s41565-020-0703-8
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发表时间：
2020-06-01
影响因子：
38.3
通讯作者：
Liu, Luqiao
中科院分区：
文献类型：
--
作者：
Han, Jiahao;Zhang, Pengxiang;Liu, Luqiao
反铁磁体（AFM）在自旋电子学中具有很大的潜力，因为它们不受外部磁场干扰，没有杂散场或太赫兹范围内的共振（1，2）。绝缘AFM与自旋轨道材料（3-7）的耦合使得能够经由AFM磁振子进行自旋输运。特别是，自旋传输超过几微米发生在一些AFM与易轴各向异性（8，9）。具有两个正交的线偏振磁振子本征模的易平面AFM在超快磁动力学的低能控制方面具有独特的优势（2）。然而，人们通常认为，这些磁振子模式不太可能传输自旋，因为它们的角动量消失（9-11）。在这里，我们报告的实验证据表明，易平面绝缘原子力显微镜，α-Fe 2 O3薄膜，可以有效地传输超过微米的距离自旋。自旋衰减长度显示出一种非常规的温度依赖性，不能单独考虑热磁振子散射捕获。我们解释我们的观察中的两个线性偏振，传播磁振子的干涉在光学中的双折射效应类比。此外，我们的器件可以在零剩余磁场下实现100%开/关比的双稳态自旋电流开关。这些发现提供了额外的工具，非易失性，低场控制的自旋输运在AFM systems. Easy平面反铁磁材料的承诺，在未来的自旋电子学应用的超快磁动力学的低能量控制，但主机磁振子与消失的角动量，这使得自旋输运通过磁振子不太可能。通过两个线性极化的传播磁振子的干涉，在微米距离上的自旋输运是可能的。
Antiferromagnets (AFMs) possess great potential in spintronics because of their immunity to external magnetic disturbance, the absence of a stray field or the resonance in the terahertz range(1,2). The coupling of insulating AFMs to spin-orbit materials(3-7) enables spin transport via AFM magnons. In particular, spin transmission over several micrometres occurs in some AFMs with easy-axis anisotropy(8,9). Easy-plane AFMs with two orthogonal, linearly polarized magnon eigenmodes own unique advantages for low-energy control of ultrafast magnetic dynamics(2). However, it is commonly conceived that these magnon modes are less likely to transmit spins because of their vanishing angular momentum(9-11). Here we report experimental evidence that an easy-plane insulating AFM, an alpha-Fe2O3 thin film, can efficiently transmit spins over micrometre distances. The spin decay length shows an unconventional temperature dependence that cannot be captured considering solely thermal magnon scatterings. We interpret our observations in terms of an interference of two linearly polarized, propagating magnons in analogy to the birefringence effect in optics. Furthermore, our devices can realize a bi-stable spin-current switch with a 100% on/off ratio under zero remnant magnetic field. These findings provide additional tools for non-volatile, low-field control of spin transport in AFM systems.Easy-plane antiferromagnet materials promise low-energy control of ultrafast magnetic dynamics in future spintronics applications, but host magnons with vanishing angular momentum, which makes spin transport via magnons unlikely. Through interference of two linearly polarized propagating magnons, spin transport over micrometre distances is yet possible.