Temperature-, Light-, and Soft X-ray-Induced Spin Crossover in a Single Layer of Fe II -Pyrazolylborate Molecules in Direct Contact with Gold

Kaushik Bairagi (1) , Amandine Bellec (2) , Cynthia Fourmental (1) , Olga Iasco (3) , Jérôme Lagoute (1) , Cyril Chacon (1) , Yann Girard (4) , Sylvie Rousset (5) , Fadi Choueikani (6) , Edwige Otero (7) , Philippe Ohresser (7) , Philippe Sainctavit (8) , Marie-Laure Boillot (9) , Talal Mallah (9) , Vincent Repain (1)

1 MPQ (UMR_7162) - Laboratoire Matériaux et Phénomènes Quantiques
2 PPM - Laboratoire de Photophysique Moléculaire
3 LMI - Laboratoire des Multimatériaux et Interfaces
4 GPS - Groupe de Physique des Solides
5 UNH - Unité de Nutrition Humaine
6 DIOM - Dispositifs et Instrumentation en Optoélectronique et micro-ondes
7 SSOLEIL - Synchrotron SOLEIL
8 IMPMC - Institut de minéralogie, de physique des matériaux et de cosmochimie
9 ICMMO - Institut de Chimie Moléculaire et des Matériaux d'Orsay

Understanding the properties of spin-crossover molecules in direct contact with metals is crucial for their future integration in electronic and spintronic devices. By X-ray absorption spectroscopy, we investigate the properties of Fe-II((3,5-(CH3)(2)Pz)(3)BH)(2) molecules in the form of monolayer islands on a metallic substrate, namely, Au(111). We demonstrate that the spin crossover transition can be thermally induced from the high spin state to a mixed spin state phase containing one-third of high-spin state and two-thirds of low-spin-state molecules in agreement with previous work by scanning tunneling microscopy. In addition, at 4.4 K, the spin crossover from the low spin state to the high spin state can also be induced by X-ray and by light excitations.

Domaines: Physique [physics]; Matière Condensée [cond-mat]

Kaushik Bairagi, Amandine Bellec, Cynthia Fourmental, Olga Iasco, Jérôme Lagoute, et al.. Temperature-, Light-, and Soft X-ray-Induced Spin Crossover in a Single Layer of Fe II -Pyrazolylborate Molecules in Direct Contact with Gold. Journal of Physical Chemistry C, 2017, 122 (1), pp.727-731. ⟨10.1021/acs.jpcc.7b11874⟩. ⟨hal-02291546⟩