Subgap Collective Tunneling and Its Staircase Structure in Charge Density Waves

Yu I. Latyshev (1) , Pierre Monceau (2) , Serguey Brazovskii (3) , A. Orlov (1) , T. Fournier (2)

1 IRE
2 CRTBT - Centre de Recherches sur les Très Basses Températures
3 LPTMS - Laboratoire de Physique Théorique et Modèles Statistiques

Tunneling spectra of chain materials NbSe3 and TaS3 were studied in nanoscale mesa devices. Current-voltage I-V characteristics related to all charge density waves (CDWs) reveal universal spectra within the normally forbidden region of low V, below the electronic CDW gap 2. The tunneling always demonstrates a threshold Vt0.2, followed, for both CDWs in NbSe3, by a staircase fine structure. T dependencies of Vt(T) and (T) scale together for each CDW, while the low T values Vt(0) correlate with the CDWs' transition temperatures Tp. Fine structures of CDWs perfectly coincide when scaled along V/. The results evidence the sequential entering of CDW vortices (dislocations) in the junction area with the tunneling current concentrated in their cores. The subgap tunneling proceeds via the phase channel: coherent phase slips at neighboring chains.

Domaines: Physique [physics]

Yu I. Latyshev, Pierre Monceau, Serguey Brazovskii, A. Orlov, T. Fournier. Subgap Collective Tunneling and Its Staircase Structure in Charge Density Waves. Physical Review Letters, 2006, 96, pp.116402. ⟨10.1103/PhysRevLett.96.116402⟩. ⟨hal-00022228⟩