Electric field effects, Mott insulator, Surface patterning, Scanning tunneling microscopy, Transition metal chalcogenides

TL;DR

This study demonstrates a strong electromechanical coupling in GaTa4Se8, enabling nano-patterning via STM by applying electric fields that induce surface inflation and crater formation, with potential applications in high-density data storage.

Contribution

First experimental evidence of electromechanical coupling in GaTa4Se8 enabling reproducible nano-writing with STM at room temperature.

Findings

Surface becomes mechanically unstable above 1.1V bias.

Nanometer-sized craters can be written and read at room temperature.

Electromechanical coupling may explain resistive switching phenomena.

Abstract

We report the first experimental evidence for a strong electromechanical coupling in the Mott insulator GaTa4Se8 allowing a highly reproducible nano-writing with a Scanning Tunneling Microscope (STM). The local electric field across the STM junction is observed to have a threshold value above which the clean (100) surface of GaTa4Se8 becomes mechanically instable: At voltage biases V > 1.1V the surface suddenly inflates and comes in contact with the STM tip, resulting in nanometer size craters. The formed pattern can be indestructibly "read" by STM at lower voltage bias, thus allowing a 5 Tdots/inch2 dense writing/reading at room temperature. The discovery of the electromechanical coupling in GaTa4Se8 might give new clues in the understanding of the Electric Pulse Induced Resistive Switching recently observed in this stoechiometric Mott insulator.