Ferromagnetic channels subject to spin injection at one extremum sustain long-range coherent textures that carry spin currents known as dissipative exchange flows (DEFs). In the weak injection regime, spin currents carried by DEFs decay algebraically and extend through the length of the channel, a regime known as spin superfluidity. Similar to fluids, these structures are prone to phase slips that manifest as vortex-antivortex pairs. Here, we numerically study vortex shedding from DEFs excited in a magnetic nanowire with a physical obstacle. Using micromagnetic simulations, we find regimes of laminar flow and vortex shedding as a function of obstacle position tunable by the spin injection sign and magnitude. Vortex-antivortex pairs translate forward (VF regime) or backward (VB regime) with respect to the detector's extremum, resulting in well-defined spectral features. Qualitatively similar results are obtained when temperature, anisotropy, and weak nonlocal dipole fields are included in the simulations. These results provide clear features associated with DEFs that may be detected experimentally in devices with nominally identical boundary conditions. Furthermore, our results suggest that obstacles can be considered as DEF control gates, opening an avenue to manipulate DEFs via physical defects.

中文翻译：

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铁磁通道中的耗散交换流可控的涡旋脱落

在一个极点处进行自旋注入的铁磁通道会维持长距离相干纹理，该纹理会携带自旋电流，称为耗散交换流（DEF）。在弱注入状态下，DEF携带的自旋电流代数衰减，并延伸通过通道的长度，这种状态称为自旋超流。与流体相似，这些结构易于出现相移，表现为涡旋-反涡旋对。在这里，我们对在具有物理障碍的磁性纳米线中激发的DEF的涡旋脱落进行了数值研究。使用微磁模拟，我们发现层流和涡流脱落的形式随障碍物位置的变化而变化，该障碍物的位置可通过自旋注入符号和幅度进行调整。涡旋-反涡旋对相对于探测器的极端向前（VF体制）或向后（VB体制）平移，产生明确的光谱特征。当在模拟中包括温度，各向异性和弱的非局部偶极子场时，可以获得定性相似的结果。这些结果提供了与DEF相关的清晰特征，可以在名义上具有相同边界条件的设备中通过实验检测到。此外，我们的结果表明，可以将障碍视为DEF控制门，这为通过物理缺陷操纵DEF提供了途径。