Dynamics of charge density wave ring

We investigate the ac conductivity of charge density wave (CDW) rings, which are topologically different from whiskers. We synthesize ring crystals of NbSe3, a CDW material, by the selenium droplet spooling method. The ac conductivity is measured for both the rings and the whiskers in the frequency range of 10 kHz-150 MHz. We analyze the frequency dependence of the ac conductivity of the CDW rings and the whiskers using a simple washboard potential model. The result suggests that the CDW rings have a larger effective mass and a higher pinning frequency than the CDW in the whiskers and that the topology of the crystals plays an important role in CDW dynamics.