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Multilevel Resistance Switching and Enhanced Spin Transition Temperature in Single- and Double-Molecule Spin Crossover Nanogap Devices

Gee, Alex; Jaafar, Ayoub H; Brachňaková, Barbora; Massey, Jamie; Marrows, Christopher H; Šalitroš, Ivan; Kemp, N. T.

Authors

Alex Gee

Ayoub H Jaafar

Barbora Brachňaková

Jamie Massey

Christopher H Marrows

Ivan Šalitroš

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Dr Neil Kemp N.Kemp@hull.ac.uk
Director of Postgraduate Researchers (Physics and Mathematics), Senior Lecturer in Physics



Contributors

Abstract

Spin crossover (SCO) molecules are promising bi-stable magnetic switches with applications in molecular spintronics. However, little is known about the switching effects of a single SCO molecule when it is confined between two metal electrodes. Here we examine the switching properties of a [Fe(III)(EtOSalPet)(NCS)] SCO molecule that is specifically tailored for surface deposition and binding to only one gold electrode in a nanogap device. Temperature dependent conductivity measurements on SCO molecule containing electromigrated gold break junctions show voltage independent telegraphic-like switching between two resistance states at temperature below 200 K. The transition temperature is very different from the transition temperature of 83 K that occurs in a bulk film of the same material. This indicates that the bulk, cooperative SCO phenomenon is no longer preserved for a single molecule and that the surface interaction drastically increases the temperature of the SCO phenomenon. Another key finding of this work is that some devices show switching between multiple resistance levels. We propose that in this case, two SCO molecules are present within the nanogap with both participating in the electronic transport and switching. Introduction The ability of spin crossover (SCO) compounds to exist in a bi-stable spin configuration makes them an attractive candidate for constructing new spintronic devices. SCO compounds have already been employed in the design of electromechanical actuators, 1 thermochromic displays 2 and data storage. 3 However, there remains a long way to go from current research to the ultimate goal of using these compounds as the building blocks of an electrically addressable memory technology, especially in the case of miniaturising towards the molecular scale and even single molecule devices. 4 The SCO phenomenon has been known about since the 1930s, 5 where it was discovered that certain compounds can undergo a transition between a high spin (HS) and low spin (LS) state via the application of

Citation

Jaafar, A. H., Marrows, C. H., Gee, A., Jaafar, A. H., Brachňaková, B., Massey, J., …Kemp, N. T. (2020). Multilevel Resistance Switching and Enhanced Spin Transition Temperature in Single- and Double-Molecule Spin Crossover Nanogap Devices. Journal of physical chemistry. C, 124(24), 13393-13399. https://doi.org/10.1021/acs.jpcc.0c03824

Journal Article Type Article
Acceptance Date May 30, 2020
Online Publication Date May 30, 2020
Publication Date Jun 18, 2020
Deposit Date Feb 9, 2021
Publicly Available Date May 31, 2021
Journal The Journal of Physical Chemistry C
Print ISSN 1932-7447
Electronic ISSN 1932-7455
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 124
Issue 24
Pages 13393-13399
DOI https://doi.org/10.1021/acs.jpcc.0c03824
Keywords Gold; Molecules; Electrodes; Quantum mechanics; Nanogaps
Public URL https://hull-repository.worktribe.com/output/3514637
Publisher URL https://pubs.acs.org/doi/10.1021/acs.jpcc.0c03824#
Related Public URLs http://eprints.whiterose.ac.uk/161425/