A chiral spin soliton lattice (CSL), one of the representative systems of a magnetic superstructure, exhibits reconfigurability in periodicity over a macroscopic length scale. Such coherent and tunable characteristics of the CSL lead to an emergence of elementary excitation of the CSL as phononlike modes due to translational symmetry breaking and bring a controllability of the dispersion relation of the CSL phonon. Using a broadband microwave spectroscopy technique, we directly found that higher-order magnetic resonance modes appear in the CSL phase of a chiral helimagnet ${\mathrm{CrNb}}_3{\mathrm{S}}_6$, which is ascribed to the CSL phonon response. The resonance frequency of the CSL phonon can be tuned between 16 and 40 GHz in the vicinity of the critical field, where the CSL period alters rapidly. The frequency range of the CSL phonon is expected to extend over 100 GHz as extrapolated on the basis of the theoretical model. The present results indicate that chiral helimagnets could work as materials useful for broadband signal processing in the millimeter-wave band.

中文翻译：

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具有可调谐磁振子色散的手性自旋孤子晶格中集体共振模式的观察

手性自旋孤子晶格（CSL）是磁性超结构的代表性系统之一，在宏观长度尺度上表现出周期性的可重构性。由于平移对称性破坏，CSL 的这种相干和可调特性导致 CSL 的基本激发出现为类声子模式，并带来 CSL 声子色散关系的可控性。使用宽带微波光谱技术，我们直接发现高阶磁共振模式出现在手性螺旋磁体的 CSL 相中${\mathrm{铬铌}}_3{\mathrm{小号}}_6$，这归因于 CSL 声子响应。在临界场附近，CSL 声子的共振频率可以在 16 到 40 GHz 之间调谐，这里 CSL 周期迅速变化。根据理论模型推断，CSL 声子的频率范围预计将超过 100 GHz。目前的结果表明，手性螺旋磁体可以作为用于毫米波段宽带信号处理的材料。