An experimental set up to probe the quantum transport through single atomic/molecular junction at room temperature

TL;DR

This paper describes the development of a room-temperature mechanically controllable break junction setup for probing quantum transport in atomic and molecular junctions, demonstrating quantized conductance and molecular junction formation.

Contribution

It introduces a novel, piezo-controlled MCBJ setup capable of measuring quantum transport at room temperature, including conductance quantization and molecular junction characterization.

Findings

Quantized conductance up to ~20 G_0 observed at room temperature.

Successful formation of single molecular junctions with bipyridine.

Demonstration of a reliable, ambient-condition quantum transport measurement technique.

Abstract

Understanding the transport characteristics at the atomic limit is the prerequisite for futuristic nano-electronic applications. Among various experimental procedures, mechanically controllable break junction (MCBJ) is one of the well adopted experimental technique to study and control the atomic or molecular scale devices. Here, we present the details of the development of a piezo controlled table top MCBJ set up, working at ambient condition, along with necessary data acquisition technique and analysis of the data. We performed conductance experiment on a macroscopic gold wire, which exhibits quantized conductance plateau upon pulling the wire with the piezo. Conductance peak up to $\sim 20 G_0$ ($G_0 = 2e^2/h$, $e$ being the electronic charge and $h$ being the plank's constant) could be resolved at room temperature. A well-known test bed molecule,$4, 4^\prime$ bipyridine, was introduced between the gold electrodes and conductance histogram exhibits two distinctive conductance peaks, confirming the formation of single molecular junction, in line with the previous reports. This demonstrate that our custom-designed MCBJ set up is capable of measuring quantum transport of a single molecular junction at ambient condition.