Department of Physics, Texas A&M University, College Station, Texas 77843-4242, USA.
Phys Rev Lett. 2012 Mar 9;108(10):107203. doi: 10.1103/PhysRevLett.108.107203. Epub 2012 Mar 7.
We show that helical magnets exhibit a nontrivial type of domain wall consisting of a regular array of vortex lines, except for a few distinguished orientations. This result follows from topological consideration and is independent of the microscopic models. We used simple models to calculate the shape and energetics of vortex walls in centrosymmetric and noncentrosymmetric crystals. Vortices are strongly anisotropic, deviating from the conventional Berezinskii-Kosterlitz-Thouless form. The width of the domain walls depend only weakly on the magnetic anisotropy, in contrast to ferromagnets and antiferromagnets. We show that vortex walls can be driven by external currents and in multiferroics also by electric fields.
我们表明，螺旋磁体表现出一种非平凡的畴壁类型，除了少数几个特殊的取向外，它由规则的涡旋线阵列组成。这一结果源于拓扑考虑，与微观模型无关。我们使用简单的模型计算了中心对称和非中心对称晶体中涡旋壁的形状和能量。涡旋是各向异性很强的，偏离了传统的 Berezinskii-Kosterlitz-Thouless 形式。畴壁的宽度仅与磁场各向异性有微弱的依赖关系，这与铁磁体和反铁磁体不同。我们表明，涡旋壁可以由外部电流驱动，在多铁性体中也可以由电场驱动。
