Electrical control over the Fe(II) spin crossover in a single molecule: Theory and experiment

Abstract

We report on theoretical and experimental work involving a particular molecular switch, an [Fecomplex, that utilizes a spin transition ("crossover"). The hallmark of this transition is a change of the spin of the metal ion, S Fe = 0 to S Fe = 2, at fixed oxidation state of the Fe ion. Combining density functional theory and first principles calculations, we demonstrate that within a single molecule this transition can be triggered by charging the ligands. In this process the total spin of the molecule, combining metal ion and ligands, crosses over from S = 0 to S = 1. Three-terminal transport through a single molecule shows indications of this transition induced by electric gating. Such an electric field control of the spin transition allows for a local, fast, and direct manipulation of molecular spins, an important prerequisite for molecular spintronics.

Assessment of density functional theory for iron(II) molecules across the spin-crossover transition

“…In some interesting works, 14,28,29,48,49 wave-function based methods were considered (see discussion below). However, unfortunately, the authors themselves admitted that their results were plagued by a number of systematic errors.…”

A Molecular Platinum Cluster Junction: A Single-Molecule Switch

“…This could provide an alternate design strategy for molecular devices other than through purely organic molecules due to the wealth of different structures possible via inorganic chemistry. Recent progress in implementing a gate in single-molecule based devices [42][43][44][45] allows us to predict for the studied molecule, with its controlled binding to the electrodes and with its two levels aligned at the Fermi level, that it could be used in a three-terminal device in which only a small gate voltage would be enough to pass through two high/low sequential switching states.…”

Robust spin crossover and memristance across a single molecule

“…For instance, molecular switches 2 may serve as highdensity memory devices. As a promising molecular class, spincrossover (SCO) complexes 3 contain a transition metal ion that can be switched between a low-spin (LS) and a high-spin (HS) state by external stimuli as temperature, light, pressure, magnetic or electric fields or charge flow [4][5][6][7][8][9][10] . The two configurations may lead to different conductances but, more importantly, the switchable spin of the metal ion has a high potential for molecular spintronics 11 .…”