论文标题
在四方沮丧的抗铁磁铁中,热力学稳定的天际晶格与偶极相互作用
Thermodynamically stable skyrmion lattice in tetragonal frustrated antiferromagnet with dipolar interaction
论文作者
论文摘要
受到GDRU $ _2 $ si $ _2 $的最新实验结果的动机[Khanh,n.d.,Nakajima,T.,Yu,Yu,X。et al。,\ Emph {Nat。纳米技术。} \ textbf {15},444-449(2020)],其中观察到纳米纳米平方skyrmion晶格,我们提出了对中央对称性抗抗抗抗磁反应型二皮极互动的中心对称性抗抗抗抗速率型的高温部分的简单分析平均均值描述。在相互的空间中,偶极力提供依赖动量的双轴各向异性。结果表明,在$ AB $平面中相互垂直的调制向量的大部分的四方晶格中,这种各向异性具有相互垂直的易于轴和共线中间轴,这导致了双Q调制自旋结构稳定性。事实证明,后者是其稳定区域的大部分的正方形晶格,拓扑充电$ \ pm $ \ pm每个磁性单位电池是由沮丧的交换耦合决定的,因此是纳米仪大小的。在存在其他单离子易于轴各向异性的情况下,可以交换易于和中间轴,从而导致不同的相图。有人认为,后一种情况与gdru $ _2 $ si $ _2 $有关。
Motivated by recent experimental results on GdRu$_2$Si$_2$ [Khanh, N.D., Nakajima, T., Yu, X. et al., \emph{Nat. Nanotechnol.} \textbf{15}, 444-449 (2020)], where nanometric square skyrmion lattice was observed, we propose simple analytical mean-field description of the high-temperature part of the phase diagram of centrosymmetric tetragonal frustrated antiferromagnets with dipolar interaction in the external magnetic field. In the reciprocal space dipolar forces provide momentum dependent biaxial anisotropy. It is shown that in tetragonal lattice in the large part of the Brillouin zone for mutually perpendicular modulation vectors in the $ab$ plane this anisotropy has mutually perpendicular easy axes and collinear middle axes, what leads to double-Q modulated spin structure stabilization. The latter turns out to be a square skyrmion lattice in the large part of its stability region with the topological charge $\pm 1$ per magnetic unit cell, which is determined by the frustrated exchange coupling, and, thus, nanometer-sized. In the presence of additional single-ion easy-axis anisotropy, easy and middle axes can be swapped, which leads to different phase diagram. It is argued that the latter case is relevant to GdRu$_2$Si$_2$.