Robust and Selective Switching of an Fe^III Spin-Crossover Compound on Cu₂N/Cu(100) with Memristance Behavior

Abstract

The switching between two spin states makes spin-crossover molecules on surfaces very attractive for potential applications in molecular spintronics. Using scanning tunneling microscopy, the successful deposition of [Fe(pap)] (pap = N-2-pyridylmethylidene-2-hydroxyphenylaminato) molecules on CuN/Cu(100) surface is evidenced. The deposited Fe spin-crossover compound is controllably switched between three different states, each of them exhibiting a characteristic tunneling conductance. The conductance is therefore employed to readily read the state of the molecules. A comparison of the experimental data with the results of density functional theory calculations reveals that all Fe(pap) molecules are initially in their high-spin state. The two other states are compatible with the low-spin state of the molecule but differ with respect to their coupling to the substrate. As a proof of concept, the reversible and selective nature of the switching is used to build a two-molecule memory.

Influence of Substrate Electronic Properties on the Integrity and Functionality of an Adsorbed Fe(II) Spin-Crossover Compound

“…A similar behavior has been observed for other SCO compounds on Au(111) 28,30,31 with exceptions 27,45 . Resorting to less metallic surfaces, on the other hand, has shown to promote the integrity of the molecules along with improved switching properties relative to metallic substrates 25,30,33,36 . We employed graphene on Ni(111) as a substrate because it can combine two aspects.…”

Spin-Crossover Complexes in Direct Contact with Surfaces

“…Note that several derivatives of these compounds may exist. Most of the compounds listed in Table 1 have been investigated as ultra-thin layers [24,31,35,[37][38][39]41,42,48,52,57,59,60,62,63,69] and single SCO complexes [29,30,32,33,67] on surfaces almost exclusively using (low-temperature) scanning tunneling microscopy (STM) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Besides sublimation, electrospray-ionization deposition has been employed to prepare samples in ultra-high vacuum environments for single-molecule investigations [25,29,70].…”

“…[28] that focuses on sublimable SCO compounds. While reversible switching of individual molecules on surfaces [25,30,31,38,67] as well as nearly full light-induced spin-state conversion of sub-monolayer coverages [24,41,52,69] have been evidenced for a number of systems, the surfaces appears to play a major role for the integrity and functionality of the adsorbed SCO complexes. In short, the strong interaction between the molecules and the metal surfaces tends to suppress their spin-state bistability (here we refer to the bistability of a single molecule.…”

Fragmentation and Distortion of Terpyridine-Based Spin-Crossover Complexes on Au(111)

“…[1][2][3][4][5][6][7][8][9][10][11] Considerable effort has been made to prepare such complexes on surfaces, e. g. for electrical contacting. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] To enable physical vapor deposition, which is the most common technique for obtaining high-quality films, compounds with increased thermal stability have been synthesized. However, even for such robust compounds, fragmen-tation issues have been reported.…”