Aqeel Aisha, Sahliger Jan, Taniguchi Takuya, Mändl Stefan, Mettus Denis, Berger Helmuth, Bauer Andreas, Garst Markus, Pfleiderer Christian, Back Christian H
Physik-Department, Technische Universität München, D-85748 Garching, Germany.
École Polytechnique Federale de Lausanne, CH-1015 Lausanne, Switzerland.
Phys Rev Lett. 2021 Jan 8;126(1):017202. doi: 10.1103/PhysRevLett.126.017202.
In the cubic chiral magnet Cu_{2}OSeO_{3} a low-temperature skyrmion state (LTS) and a concomitant tilted conical state are observed for magnetic fields parallel to ⟨100⟩. Here, we report on the dynamic resonances of these novel magnetic states. After promoting the nucleation of the LTS by means of field cycling, we apply broadband microwave spectroscopy in two experimental geometries that provide either predominantly in-plane or out-of-plane excitation. By comparing the results to linear spin-wave theory, we clearly identify resonant modes associated with the tilted conical state, the gyrational and breathing modes associated with the LTS, as well as the hybridization of the breathing mode with a dark octupole gyration mode mediated by the magnetocrystalline anisotropies. Most intriguingly, our findings suggest that under decreasing fields the hexagonal skyrmion lattice becomes unstable with respect to an oblique deformation, reflected in the formation of elongated skyrmions.
在立方手性磁体Cu₂OSeO₃中，对于平行于⟨100⟩的磁场，观察到一种低温斯格明子态（LTS）以及伴随的倾斜圆锥态。在此，我们报道这些新型磁态的动态共振。通过场循环促进LTS的成核后，我们在两种实验几何结构中应用宽带微波光谱，这两种几何结构分别提供主要的面内或面外激发。通过将结果与线性自旋波理论进行比较，我们清楚地识别出与倾斜圆锥态相关的共振模式、与LTS相关的旋转和呼吸模式，以及由磁晶各向异性介导的呼吸模式与暗八极旋转模式的杂化。最有趣的是，我们的发现表明，在磁场降低时，六角形斯格明子晶格相对于倾斜变形变得不稳定，这反映在拉长的斯格明子的形成上。
