Achieving high velocities of magnetic domain walls is a crucial factor for their use as information carriers in modern nanoelectronic applications. In nanomagnetism and spintronics, these velocities are often limited either by internal domain wall instabilities, known as the Walker breakdown phenomenon, or by spin wave emission, known as the magnonic regime. In the rigid domain wall model, the maximum magnon velocity acts as an effective “speed of light”, providing a relativistic analogy for the domain wall speed limitation. Cylindrical magnetic nanowires are an example of systems without the Walker breakdown phenomenon. Here we demonstrate that the magnonic limit could be outstandingly surpassed in cylindrical nanowires with high magnetization, such as iron. Our numerical modeling shows the Bloch point domain wall velocities as high as 14 km s⁻¹, well above the magnonic limit estimated in the interval 1.7–2.0 km s⁻¹. The key ingredient is the three-dimensional conical shape of the domain wall, which elongates and breaks during the dynamics, expelling backwards pairs of Bloch points. This leads to domain wall acceleration, the effect, which resembles the “jet propulsion”. This effect will be very important for three-dimensional networks based on cylindrical magnetic nanowires.

中文翻译：

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圆柱形铁磁纳米线中的巨型超磁波布洛赫点速度

实现磁畴壁的高速是其在现代纳米电子应用中用作信息载体的关键因素。在纳米磁性和自旋电子学中，这些速度通常受到内部畴壁不稳定性（称为沃克击穿现象）或自旋波发射（称为磁振态）的限制。在刚性畴壁模型中，最大磁振子速度充当有效的“光速”，为畴壁速度限制提供了相对论类比。圆柱形磁性纳米线是没有沃克击穿现象的系统的一个例子。在这里，我们证明了具有高磁化强度的圆柱形纳米线（例如铁）可以显着超越磁极极限。我们的数值模型显示布洛赫点畴壁速度高达 14 km s ^{-1 ，远高于 1.7-2.0 km s -1}区间内估计的声速极限。关键成分是畴壁的三维圆锥形状，它在动力学过程中伸长和断裂，向后排出布洛赫点对。这会导致磁畴壁加速，其效果类似于“喷气推进”。这种效应对于基于圆柱形磁性纳米线的三维网络来说非常重要。