Subgap tunneling via a quantum interference effect: Insulators and charge density waves

• Published in: Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2007-11, Vol.76 (18), Article 184503
• Main Authors: Duhot, S., Mélin, R.
• Format: Article
• Language: English
• Subjects: Condensed Matter; Mesoscopic Systems and Quantum Hall Effect; Physics
• ISSN: 1098-0121; 1550-235X
• DOI: 10.1103/PhysRevB.76.184503

A quantum interference effect is discussed for subgap tunneling over a distance comparable to the coherence length, which is a consequence of “advanced-advanced” and “retarded-retarded” transmission modes [Altland and Zirnbauer, Phys. Rev. B 55, 1142 (1997)]. Effects typical of disorder are obtained from the interplay between multichannel averaging and higher order processes in the tunnel amplitudes. Quantum interference effects similar to those occurring in normal tunnel junctions explain magnetoresistance oscillations of a CDW pierced by nanoholes [Latyshev et al., Phys. Rev. Lett. 78, 919 (1997)], having periodicity h/2e as a function of the flux enclosed in the nanohole. Subgap tunneling is coupled to the sliding motion by charge accumulation in the interrupted chains. The effect is within the same trend as random matrix theory for normal metal-CDW hybrids [Visscher et al., Phys. Rev. B 62, 6873 (2000)]. We suggest that the experiment by Latyshev et al. probes weak localizationlike properties of evanescent quasiparticles, not an interference effect related to the quantum-mechanical ground state.