Dynamical switching of magnetic topology in microwave-driven itinerant magnet
Dynamical switching of magnetic topology in microwave-driven itinerant magnet
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DOI：
10.1103/physrevb.104.104425
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发表时间：
2021-09
影响因子：
3.7
通讯作者：
Rintaro Eto;M. Mochizuki
中科院分区：
文献类型：
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作者：
Rintaro Eto;M. Mochizuki
我们通过在三角晶格上采用近藤晶格模型，从理论上证明了在中心对称的巡游磁体中微波诱导的磁拓扑动态切换。已知该模型会呈现出两种具有不同磁拓扑电荷（|Nsk| = 1和2）的斯格明子晶格。我们的数值模拟表明，圆偏振微波场对共振模式的强烈激发能够切换磁拓扑，即根据微波频率，从|Nsk| = 1的斯格明子晶格切换到|Nsk| = 2的另一种斯格明子晶格，或者切换到|Nsk| = 0的非拓扑磁序。这种磁拓扑切换表现出各种不同的行为，即确定性的不可逆切换、概率性的不可逆切换以及随时间随机波动，这取决于微波频率和外磁场强度，其多样性归因于动态区域中不同的能量态势。还根据基于微扰展开推导的有效模型的时间演化方程对所得结果进行了讨论。
We theoretically demonstrate microwave-induced dynamical switching of magnetic topology in centrosymmetric itinerant magnets by taking the Kondo-lattice model on a triangular lattice, which is known to exhibit two types of skyrmion lattices with different magnetic topological charges of |Nsk| = 1 and 2. Our numerical simulations reveal that intense excitation of a resonance mode with circularly polarized microwave field can switch the magnetic topology, i.e., from the skyrmion lattice with |Nsk| = 1 to another skyrmion lattice with |Nsk| = 2 or to a nontopological magnetic order with |Nsk| = 0 depending on the microwave frequency. This magnetic-topology switching shows various distinct behaviors, that is, deterministic irreversible switching, probabilistic irreversible switching, and temporally random fluctuation depending on the microwave frequency and the strength of the external magnetic field, the variety of which is attributable to different energy landscapes in the dynamical regime. The obtained results are also discussed in the light of time-evolution equations based on an effective model derived using perturbation expansions.