Suppression of rectification at metal–Mott insulator interfaces

Kenji Yonemitsu, Nobuya Maeshima, and Tatsuo Hasegawa
Phys. Rev. B 76, 235118 – Published 18 December 2007

Abstract

Charge transport through metal–Mott insulator interfaces is studied and compared with that through metal-band-insulator interfaces. For band insulators, rectification has been known to occur owing to a Schottky barrier, which is produced by the work-function difference. For Mott insulators, however, qualitatively different current-voltage characteristics are obtained. Theoretically, we use the one-dimensional Hubbard model for a Mott insulator and attach to it the tight-binding model for metallic electrodes. A Schottky barrier is introduced by a solution to the Poisson equation with a simplified density-potential relation. The current density is calculated by solving the time-dependent Schrödinger equation. We mainly use the time-dependent Hartree-Fock approximation and also use exact many-electron wave functions on small systems for comparison. Rectification is found to be strongly suppressed even for large work-function differences. We show its close relationship with the fact that field-effect injections into one-dimensional Mott insulators are ambipolar. Experimentally, we fabricated asymmetric contacts on top of single crystals of quasi-one-dimensional organic Mott and band insulators. Rectification is strongly suppressed at an interface between metallic magnesium and Mott-insulating (BEDTTTF)(F2TCNQ) [BEDTTTF=bis(ethylenedithio)tetrathiafulvalene; F2TCNQ=2,5difluorotetracyanoquinodimethane].

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  • Received 17 September 2007

DOI:https://doi.org/10.1103/PhysRevB.76.235118

©2007 American Physical Society

Authors & Affiliations

Kenji Yonemitsu1,2,*, Nobuya Maeshima1,3, and Tatsuo Hasegawa4

  • 1Institute for Molecular Science, Okazaki 444-8585, Japan
  • 2Department of Functional Molecular Science, Graduate University for Advanced Studies, Okazaki 444-8585, Japan
  • 3Department of Chemistry, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan
  • 4Correlated Electron Research Center (CERC), AIST, Tsukuba 305-8562, Japan

  • *kxy@ims.ac.jp

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Vol. 76, Iss. 23 — 15 December 2007

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