Elektroneninduzierter Spin‐Crossover von Einzelmolekülen in einer Doppellage auf Gold

Abstract

Einzelne Moleküle des Eisen(II)‐Komplexes [Fe(bpz)2phen] (phen=1,10‐Phenanthrolin; bpz=Dihydrobis(pyrazolyl)borat) werden durch Elektronen‐induzierten Spin‐Crossover (ELIESST) in einer Doppellage auf Gold reversibel zwischen low spin und high spin geschaltet, wie durch Rastertunnelmikroskopie gezeigt wurde.

The spin state of a molecular adsorbate driven by the ferroelectric substrate polarization

“…We showed previously that thin films made by sublimation do preserve molecular integrity, 12,14,19 a result confirmed independently by other authors. [2][3][4]9 Indeed temperature-dependent magnetic properties of vacuum evaporated thin film samples measured using a superconducting quantum interference device (SQUID) magnetometer a Department of Physics and Astronomy, University of Nebraska -Lincoln, Lincoln, indicate a thermal SCO transition in agreement with earlier reports. 12,14,18 The unoccupied molecular orbitals of the iron complex [Fe(H 2 B(pz) 2 ) 2 (bipy)] thin films were characterized by inverse photoemission spectroscopies (IPES), as described elsewhere.…”

“…Low spin (LS) diamagnetic to paramagnetic high spin (HS) transitions can be induced by pressure, temperature, illumination, or magnetic pulses. 1 The possibility of inducing a SCO transition by an electric field [2][3][4][5] could lead to molecular magnetic state transition altered by an applied electric field either in the ground state or the excited state. This is attractive because molecular systems are among the very few systems where nonvolatile magnetic state switching at GHz and coercive voltages less than 2 V (ESI, † SR1) may in fact be possible.…”

“…1,6,7 This has important consequences, in particular for electronic transport properties. [3][4][5]8,9 The modification of the conductivity induced by the spin transition remains difficult to characterize, 3-5 possibly hindered by transition-induced changes of crystallinity 7 or complexities at the molecule-electrode interfaces. 10 The characterization of the electronic structure is therefore essential, and the spectroscopic signature, particularly of the unoccupied electronic structure, has been shown to be a powerful indication of electronic changes between high and low spin states.…”

Confined Crystallization of Spin‐Crossover Nanoparticles in Block‐Copolymer Micelles

“…[4,8] Furthermore,t he physical properties of either the complex itself (e.g.c olor,m agnetism, structure) [5,9] or associated properties in multifunctional systems (e.g. conductivity, [10] luminescence [11] )change upon switching and raise their interest for applications,e specially as sensors. [12] In order to realize such applications,aneasy processing of the complexes is indispensable for the integration in devices.T his task (including down-sizing) is challenging as most of the SCO properties,e specially the observation of wide thermal hysteresis loops,d epend on the crystal packing.…”

Iron(II) Spin‐Crossover Complexes in Ultrathin Films: Electronic Structure and Spin‐State Switching by Visible and Vacuum‐UV Light

“…[9,10] Successful vacuum deposition of 1 and the related complex [Fe(H 2 bpz) 2 (bipy)] (2; bipy = 2,2'-bipyridine) [11,12] has opened up the possibility to study this effect in solvent-free high-quality films, using methods that require ultra-high vacuum conditions, such as ultraviolet [13] and X-ray photoelectron or inverse photoemission spectroscopy. [14] In recent studies, thin films of 1 and 2 have also been investigated with scanning tunneling microscopy [15][16][17] as well as X-ray absorption spectroscopy, [18][19][20] and evidence for electron-induced spin-state switching has been provided for 1. [15,16] Detailed studies of the valence electronic structure of 1 and 2 are still missing, however.…”