Anisotropic microwave response in Cr_1/3TaS₂ hosting chiral magnetic soliton

Chromium-intercalated hexagonal Cr1/3TaS2 possesses exotic properties, such as high-temperature magnetic soliton, crossover of critical behavior, and nontrivial magnetism. In this study, we employ the electron spin resonance (ESR) technique to modulate and study the chiral magnetic soliton lattice (CSL) in Cr1/3TaS2 using microwave at X-band. The experimental results show that Cr1/3TaS2 has a particularly strong microwave response when H perpendicular to c but very weak feedback when H//c, revealing an anisotropic microwave response. When H perpendicular to c, the resonance peak at lower fields results from the surface barrier induced by the competition between Dzyaloshinsky-Moriya interaction, Zeeman energy, and exchange energy. The dominant resonance is caused by the ferromagnetic mode with the twisted region as the boundary condition, which transforms into a paramagnetic resonance above the phase transition temperature (T-C). Furthermore, an unusual temperature dependence of ESR spectra is revealed. The crystalline electric field (CEF) excitation owing to large strong spin-orbit coupling results in the widening of the ESR linewidth above T-C. Furthermore, an abrupt shift in the resonance field H-r2 and ESR linewidth Delta H-PP2 is observed around T-C, which is attributed to a sudden change in spin-exchange interactions and magnetic anisotropy around T-C, as Cr1/3TaS2 was previously observed for spin interaction transition from strong anisotropic 3D-Ising type to isotropic 3D-Heisenberg magnetic interaction below T-C. This work demonstrates that the ESR can detect the CSL state and investigate materials with nontrivial magnetism.