Space charge-limited current transport mechanism in crossbar junction embedding molecular spin crossovers

Giuseppe Cucinotta (1, 2) , Lorenzo Poggini (1, 2) , Niccolò Giaconi (1, 2) , Alberto Cini (2, 3) , Mathieu Gonidec (4) , Matteo Atzori (1, 2) , Enrico Berretti (5) , Alessandro Lavacchi (5) , Maria Fittipaldi (3, 2) , Aleksandr I. Chumakov (6) , Rudolf Rüffer (6) , Patrick Rosa (4) , Matteo Mannini (1, 2)

1 Department of Chemistry ''Ugo Schiff"
2 INSTM - National Interuniversity Consortium of Materials Science and Technology
3 Dipartimento di Fisica e Astronomia [Firenze]
4 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
5 ICCOM - Istituto di Chimica dei Composti Organometallici
6 ESRF - European Synchrotron Radiation Facility

Spin crossover complexes are among the most studied classes of molecular switches and have attracted considerable attention for their potential technological use as active units in multifunctional devices. A fundamental step toward their practical implementation is the integration in macroscopic devices adopting hybrid vertical architectures. First, the physical properties of technological interest shown by these materials in the bulk phase have to be retained once they are deposited on a solid surface. Herein, we describe the study of a hybrid molecular inorganic junction embedding the spin crossover complex [Fe(qnal)2] (qnal = quinoline-naphthaldehyde) as an active switchable thin film sandwiched within energy-optimized metallic electrodes. In these junctions, developed and characterized with the support of state of the art techniques including synchrotron Mössbauer source (SMS) spectroscopy and focused-ion beam scanning transmission electron microscopy, we observed that the spin state conversion of the Fe(II)-based spin crossover film is associated with a transition from a space charge-limited current (SCLC) transport mechanism with shallow traps to a SCLC mechanism characterized by the presence of an exponential distribution of traps concomitant with the spin transition temperature.

Mots clés: Spin crossover; Transport measurements; Hybrid device; FIB-STEM; Synchrotron Mössbauer spectroscopy; Molecular magnetism; Molecular spintronics

Domaines: Matériaux

Giuseppe Cucinotta, Lorenzo Poggini, Niccolò Giaconi, Alberto Cini, Mathieu Gonidec, et al.. Space charge-limited current transport mechanism in crossbar junction embedding molecular spin crossovers. ACS Applied Materials & Interfaces, 2020, 12 (28), pp.31696-31705. ⟨10.1021/acsami.0c07445⟩. ⟨hal-02906236⟩