J. Phys. IV France 114 (2004) 91
Spatially resolved tunneling spectroscopy on TTF-TCNQZ.Z. Wang1, J.C. Girard1, C. Pasquier2 and D. Jérome2
1 Laboratoire de Photonique et de Nanostructures (CNRS U.P.R 020), Route de Nozay, 91460 Marcoussis, France
2 Laboratoire de Physique des Solides (CNRS U.R.A. 8502), Bâtiment 510, Université de Paris-Sud, 91405 Orsay, France
Local tunneling spectroscopy has been measured with low temperature UHV-STM on in-situ cleaved ab surface of organic TTF-TCNQ crystal. Due to ultra low image drift and clear molecular resolution, the spectroscopy is performed at specific molecular site either on TCNQ or TTF chains. In normal state (T= 63 K), a large pseudo-gap exists both in TTF and TCNQ chains. Above pseudo-gap local density of states differs for TTF and TCNQ chains that is in good agreement with double band model. By the signature of an anomalous in local spectroscopy measurement, a single impurity has been detected on a TTF chain. Charge density wave fluctuation is pinned by impurity above critical temperature (T=54K). Results obtained show that, Scanning Tunneling Spectroscopy can provide spatially resolved spectroscopic information at nanometer scale. Key words. TTF-TCNQ, local tunneling spectroscopy, pseudogap.
© EDP Sciences 2004