"Probing Concepts in Single-Molecule Wires: Diodes, Electromechanics, FETs, Spinterfaces, etc."

Who: Ismael Diez, University of Barcelona, Barcelona, Spain

Place: nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian

Date: Monday, 9 June 2014, 11:00

Host: Luis Hueso

Single-molecule Junction approaches [1] have advanced the comprehension of charge transport in a large variety of molecular backbones and brought fine details on the molecule-electrode communication [2,3]. Latest efforts in this field have been focused on the design of nanoscale molecular contacts with new electrical functionalities [4,5].

The first block of this seminar will describe our latest implemented methodologies to univocally identify the formation of single-molecule contacts between two metal beads. The methods are based on the combination of DC-AC current detection schemes when a small AC mechanical perturbation is introduced along the main single-molecule junction axis [6].

For the second block, we have picked few examples that illustrate the exploitation of previous methodologies to tailor single-molecule wires with new electrical behaviors. The first case presents an example of controlling diode (rectification) behavior in a single-molecule device [5]. Here we demonstrate that it is possible to go from a perfectly symmetric to a highly rectifying charge transport in a single-molecule junction by introducing specific asymmetry within the molecular backbone. The second case shows an example of a single-molecule device incorporating mechanical gating capabilities [4]. The last example shows the design of single-molecule field effect transistors (FET) by exploiting an electrochemical gate method [5]. Several examples of efficient current modulation on single-molecule contact with this approach will be shown.

Last block of this seminar will focus on single-molecule wires built with more complex organometallic backbones. Such molecular systems brought a number of potential applications in nanoscale electrical interfaces, from highly efficient molecular wires [7] to spin-dependent transport applications [8]. Two new examples will be brought here: first, spin-dependent transport in a single-molecule contact built with an Fe(II)-based spin crossover (SCO) compound is presented. Large magnetoresistance (>100%) is observed at low applied biases depending upon the magnetization direction of a Ni electrode. The second example illustrates the use of the metal coordination chemistry to wire a single metalloporphyrin ring between two metal electrodes in a fully flat conformation. This special geometry allows enhanced electrical coupling between the metal electrodes and the molecule through the porphyrin metal center.



[1]. Xu, B., Tao, NJ. Science, 301 (2003) 1221.

[2]. Chen, F. et al. JACS 128 (2006) 15874.

[3]. Díez-Pérez, I. et al. Nature Nanotechnology 6 (2011) 226.

[4]. Díez-Pérez, I. et al. Nature Chemistry 1 (2009) 635.

[5]. Díez-Pérez, I. et al. Nature Comm. 1 (2010) 635.

[6]. J. Xia, I. Díez-Pérez, et al. Nano Letters 8 (2008) 1960.

[7]. Gita Sedghi et al. Nature Nanotechnology 6 (2011) 517.

[8]. Burzurí, E. et al. Physical Review Letters 109, 147203 (2012).

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