Spin dynamics of the quasi-one-dimensional antiferromagnet CuClHCSO

Fujisawa, Masashi*; Shiraki, Kosuke*; Okubo, Susumu*; Ota, Hitoshi*; Yoshida, Makoto*; Tanaka, Hidekazu*; Sakai, Toru

The spin dynamics of the quasi-one-dimensional antiferromagnet CuClHCSO was investigated by the electron spin resonance (ESR). The system has a spin gap, but the direct ESR transition of the spin gap is forbidden due to the spin conservation law, because the spin gap is an energy gap between the singlet and triplet states. However, the direct ESR transition of the spin gap was observed for this material. The present study revealed that the origin of the direct ESR transition is the Dzyaloshinsky-Moriya interaction, and applying the selection rule of the angle-dependent ESR intensity, we successfully specified the direction of the interaction vector.