Topological effects of charge density waves in ring-shaped crystals ofNbSe3

Abstract

We studied the differences of the charge density wave ͑CDW͒ dynamics in closed-ring and open-ring topologies by measuring the frequency-dependent resistance in the radio-frequency range. We performed a two-probe ac resistance measurement for a ring-shaped crystal of niobium triselenide ͑NbSe 3 ͒ in the 300 kHz to 1.3 GHz frequency range. We compared the frequency dependence of the resistance of closed-ring and open-ring crystals and found that the pinning potential in the former is smaller than that in the latter. The open-ring crystal was obtained by changing of the topology of the closed-ring crystal. We believe that the reduction in the pinning effect is caused by a CDW circulating current in the closed-ring topology.

Polyhedral Topological Crystals

“…Crystal topology broke through a new stage of understanding of physical phenomena. 12,14,15 The topological crystals are conceptually different from conventional crystals. A crystal is constructed by the infinite repetition of atoms, as shown in Figure 1 (LEFT).…”

Topological effects of the superconducting vortex state in aTaSe3ring crystal: Observation of magnetic torque oscillations

“…To confirm the topological effect, we performed a control experiment on a cut ring Sample CЈ, after measuring Sample C. Sample CЈ was obtained by cutting Sample C with a focused ion beam. 13,14 Sample cutting is an effective method for changing the topology. Figures 3͑a͒ and 3͑b͒ show the typical results of these measurements.…”

Charge-density waves at intermediate coupling

“…A smoothly sliding state is also more easily obtained with a longer sample. This cause of velocity fluctuations should be eliminated if the sample was ring shaped, as in some recent resistance experiments by Matsuura et al (2006) on NbSe 3 .…”

“…Over the past three decades, there has been a wealth of data on many CDW systems accumulated, with NbSe 3 probably being the most widely investigated (see Ong & Monceau 1977;Fleming et al 1978;Fleming & Grimes 1979;Grüner & Zettl 1985;Ségransan et al 1986;Grüner 1988Grüner , 1994Ross et al 1990;Monceau 2006;Lemay et al 1999;Ringland et al 2000;Danneau et al 2002;Requardt et al 2002;Schäfer et al 2003;Sinchenko & Monceau 2003;Perucchi et al 2004;Matsuura et al 2006; see Grüner for a review). There have also been theoretical works addressing various aspects of the problem (see Allender et al 1974;Lee et al 1974;Rice 1975;Rice et al 1976Rice et al , 1979Boriack & Overhauser 1977;McMillan 1977;Wilson 1979;Horovitz 1986;Bjelis 1987;Tucker et al 1988;Eremko 1992;McKenzie & Wilkins 1992;Buker 1999).…”