Origin of negative differential resistance in molecular junctions of Rose Bengal

TL;DR

This study demonstrates that negative differential resistance (NDR) in Rose Bengal molecular junctions can be electrically controlled and used for atomic-scale memory, highlighting the role of junction electronics in moletronics.

Contribution

It reveals that NDR can be induced and manipulated in Rose Bengal dimers and trimers on gold surfaces, enabling atomic-scale memory applications.

Findings

NDR appears only in molecular assemblies, not isolated molecules.

Electrical pulses can induce, destroy, or regenerate NDR in junctions.

Memory bits can be encoded using NDR states in molecular junctions.

Abstract

Negative differential resistance (NDR) is tuned at junctions of electronically different dimer and trimer of Rose Bengal on an atomic flat gold (111) surface. Isolated molecule did not show any NDR. But it was induced to show double NDR with large peak to valley ratio (1.8~3.1) in room temperature via charging its neighbor reproducibly by an electrical pulse. In some sections of junction by applying pulse one could destroy the phenomenon or regenerate it by STM manipulation of molecules. NDR was also independent of polaronic nature. It was possible to write bits 1 and 0 for cationic NDR (in dimer) and 00, 01, 10, 11 for di-anionic NDR (trimer) which generated 2/4 bit memory in a atomic scale junction showing importance of junction electronics in future of moletronics.