Microwave response of the chiral helimagnetic MnNb_3S_6

摘要

Chiral magnetic soliton (CMS), an isolated topological kink consisting of spins, has potential applications in spintronics. In this work, the microwave response of layered MnNb_3S_6, which is suggested as a candidate for CMS, is investigated by the electronic spin resonance (ESR). Angle-dependent ESR spectra show that the microwave response is strong for H⊥c while it is weak for H//c, where c is the c-axis of the single crystal. When H⊥c, two resonance lines are observed, which are marked as H_(r1) for the higher field and H_(r2) for the lower field. It is determined that H_(r1) originates from the ferromagnetic resonance of forced ferromagnetic moments, which evolves into paramagnetic resonance above T_c. Meanwhile, H(r2) existing only below T_c fulfills the Goldstone excitation of CMS. The microwave response of MnNb_3S_6 supports the existence of CMS in MnNb_3S_6, and is proved to be an effective means for modulating and investigating CMS.