Electrical and spin switches in single‐molecule junctions

Abstract

Single-molecule electrical and spin switches have been one of the main research focuses in molecular electronics and spintronics because they may form the most important elements for the future information technology, thus attracting great attention in the scientific community and witnessing significant progresses benefiting from the combination of physics, chemistry, materials, and engineering. The key issue of constructing single-molecule switches is the development of stimulus-responsive systems that provide bistable or multiple states. In this review, we summarize the recent advances of this field in terms of the external stimulus that induces the switching. A variety of external stimuli, such as light, electric field, magnetic field, mechanical force, and chemical stimulus, have been successfully employed to activate the reversible switching in single-molecule junctions by manipulating molecular structures, conformations, electronic states, and spin states. As a burgeoning field, we finally put forward the challenges in molecular electronics and spintronics that need to be solved, which will initiate intense research. K E Y W O R D Selectrical switch, single-molecule junction, spin switch, stimuli-responsive system

In Operando Modulation of Rectification in Molecular Tunneling Junctions Comprising Reconfigurable Molecular Self‐Assemblies

“…[ 2,3 ] By exploiting the chemical nature of molecular electronics, these effects are exemplified in photoisomerization, [ 4–8 ] , protonation, [ 9,10 ] electrostatic gating, [ 11,12 ] reduction–oxidation, [ 13 ] etc., giving rise to molecular resistors and molecular diodes in both single‐molecule junctions and large‐area junctions comprising self‐assembled monolayers (SAMs). The majority of studies on effects that rely on external inputs, such as conductance switching, are observed ex situ, i.e., new junctions are formed and characterized instead of molecules being switched in‐place, be they single‐molecule break‐junctions in which molecules are repeatedly trapped and released [ 14 ] or large‐area junctions formed by raising and lowering a tip on top of a SAM. [ 9 ] Static, single‐molecule junctions that exhibit in situ conductance switching often suffer from instability at room temperature and low yield of working junctions; [ 8,15 ] device‐like, large‐area junctions comprising SAMs, on the contrary, have demonstrated reproducible conductance switching at ambient conditions.…”

Advances and challenges in single-molecule electron transport

“…Many forms of switching in single-molecule junctions have been investigated, and a recent review was given by Ke et al (2020). The magnetic degrees of freedom of molecular matter have been investigated in the fields of molecular magnets and molecular spintronics.…”

A single-molecule electrical approach for amino acid detection and chirality recognition

“…Among single-molecule techniques ( 16 , 17 ), graphene-molecule-graphene single-molecule junctions (GMG-SMJs) are particularly useful because they have the unique ability of covalently incorporating individual molecular systems behaving as the conductive channel into an electrical nanocircuit, which solves the challenges of the fabrication difficulty and poor device stability. This approach has proven to be a robust platform of single-molecule electronics that is capable of creating molecular optoelectronic devices ( 18 – 21 ) and probing the dynamic processes of submolecular changes at the single-event level with high temporal resolution and high signal-to-noise ratios ( 22 ), for example, carbon cation formation ( 23 ), photoinduced conformational transition ( 24 ), nucleophilic addition ( 25 ), and cocaine detection ( 26 ).…”