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Transition voltage spectroscopy in vacuum break junction: The standard tunneling barrier model and beyond
Author(s) -
Bâldea Ioan,
Köppel Horst
Publication year - 2012
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201248034
Subject(s) - quantum tunnelling , spectroscopy , break junction , condensed matter physics , materials science , physics , chemical physics , quantum mechanics
Recent experiments on transition voltage ( V t ) spectroscopy in mechanically controllable vacuum break junctions have been interpreted theoretically by using a Simmons WKB‐type approach of the transport by tunneling based on the standard vacuum barrier picture (work function + source‐drain bias + charge images). In the first part of the paper, we present an analysis demonstrating the inconsistencies of that approach. Then, we report detailed results obtained by exactly solving the Schrödinger equation, which show that the standard tunneling barrier model fails to describe the experimental vacuum transition voltage spectroscopy (TVS) data. This indicates that the physical description within that model is incomplete. In the attempt to go beyond the standard barrier model, we report results demonstrating that the inclusion of electron states at the electrodes' surface significantly improves the agreement with experiment. This applies both to the d ‐dependence of V t and to the jump in the linear conductance when approaching the atomic contact limit.