Nonlocal transport in the charge density waves ofo-TaS3

Abstract

We studied the nonlocal transport of a quasi-one-dimensional conductor o-TaS 3 . Electric transport phenomena in charge density waves include the thermally excited quasiparticles and collective motion of charge density waves ͑CDWs͒. In spite of its long-range correlation, the collective motion of a CDW does not extend far beyond the electrodes, where phase slippage breaks the correlation. We found that nonlocal voltages appeared in the CDW of o-TaS 3 , both below and above the threshold field for CDW sliding. The temperature dependence of the nonlocal voltage suggests that the observed nonlocal voltage originates from the CDW even below the threshold field. Moreover, our observation of nonlocal voltages in both the pinned and sliding states reveals the existence of a carrier with long-range correlation, in addition to sliding CDWs and thermally excited quasiparticles. Nonlocal properties in charge density waves ͑CDWs͒ have been attracting interest for decades.1-3 Since electric transport phenomena include collective motion, 4 it is natural to expect a sliding CDW to be a possible source of nonlocal transport.1 The correlation of the CDW phase has been estimated in the 1 -100 m range, 1,5-13 which is long enough to allow experimental studies. The correlation inside the sliding region has been confirmed. However, it has been shown that the correlation of a sliding CDW does not extend far beyond the electrodes, where phase slippage may destroy the correlation. 2,3In this Brief Report, we report a nonlocal transport phenomenon with a quasi-one-dimensional conductor o-TaS 3 . Following the pioneering work by Gill, 1 we compared current-voltage characteristics obtained with normal and transposed electrode configurations, as well as with nonlocal detection ͑Fig. 1͒. We found that nonlocal voltages appeared in the CDW of o-TaS 3 , both below and above the threshold field for CDW sliding. The sign of the observed nonlocal voltage was opposite to that of the spreading resistance. 14,15 In addition to this, the temperature dependence of the nonlocal voltage suggests that the observed nonlocal voltage originates from the CDW. Moreover, our observation of nonlocal voltages in both the pinned and sliding states reveals the existence of a carrier with long-range correlation, in addition to sliding CDWs and thermally excited quasiparticles. Finally, we compared our observation to the coexistence of two CDWs in o-TaS 3 ͑Refs. 16 and 17͒ and found it is closely related to topological dislocations in CDWs.We performed a four-probe measurement, which requires a voltmeter with a high input impedance so that the leakage current to the voltmeter becomes negligible. For fully gapped CDW materials, such as o-TaS 3 , the use of four-probe measurement is usually difficult especially at low temperatures where the sample resistance often exceeds the typical input impedance of a voltmeter, for example, Z in ϳ 1 G⍀. We exploited an electrometer ͑Keithley 6512, Z in Ͼ 200 T⍀͒ to measure the voltage drop of the o-TaS 3 samples.o-TaS 3 crystals ...

Field-induced dielectric response saturation ino-TaS3

“…The temperature dependent resistivity along the chain direction of o-TaS 3 specimens is consistent with previous results [21][22][23][24] . Below Peierls transition temperature T p = 220 K, two electric thresholds reveal on the I-V curves, see Fig.…”

“…2 (b)-IV, but for thicker samples case would be changed inversely and thus no E T −N features. As expected, typical volume of the throughout coherent CDW domain (TCCD) would be up to a macroscopic volume 13,23 . With decreasing temperature, the absolute value of E T −N increases monotonically.…”

Charge density wave soliton liquid

“…Phase solitons have been expected in the one-dimensional CDW system of orthorhombic tantalum trisulfide (o-TaS 3 ) crystals to explain the CDW transport properties [2][3][4], and the Aharonov-Bohm interference in o-TaS 3 rings [5,6]. In addition, the coexistence of commensurate and incommensurate CDWs in o-TaS 3 crystals was observed below the Peierls transition temperature T P = 218 K by X-ray diffraction [7].…”

Possible origin of nonlinear conductivity and large dielectric constant in the commensurate charge-density-wave phase of 1T−TaS2

“…The existence of CDW phase solitons -topological phase defects -is a particular form of collective excitation in the CDW condensate and has been confirmed in quasi-1D systems [54][55][56][57]. Recently, there are suggestions that soliton contribution must be rather important for the unconventional transport properties associated with CDW system [58][59][60] In Ref. [35], Krive and Rozhavsky proposed that the phase solitons significantly contribute the dielectric susceptibility.…”