Unprecedented size effect on the phase stability of molecular thin films displaying a spin transition

Victoria Shalabaeva (1, 2) , Mirko Mikolasek (3) , Maria Dolores Manrique-Juarez (1, 2) , Alin-Ciprian Bas (1, 2) , Sylvain Rat (1, 2) , L. Salmon (1) , William Nicolazzi (1, 2) , Gábor Molnár (1) , Azzedine Bousseksou (1)

1 LCC - Laboratoire de chimie de coordination
2 UT3 - Université Toulouse III - Paul Sabatier
3 ESRF - European Synchrotron Radiation Facility

An unexpected upshift of the spin transition temperature by ca. 3 K is observed in thermally evaporated films of the [FeII(HB(tz)3)2] (tz = 1,2,4-triazol-1-yl) complex when reducing the film thickness from ca. 200 to 45 nm. Fitting the experimental data to continuum mechanics and thermodynamical models allows us to propose an explanation based on the anisotropy of the transformation strain leading to ∼5 mJ/m2 higher 00l surface energy in the high-spin phase.

Domaines: Chimie de coordination

Victoria Shalabaeva, Mirko Mikolasek, Maria Dolores Manrique-Juarez, Alin-Ciprian Bas, Sylvain Rat, et al.. Unprecedented size effect on the phase stability of molecular thin films displaying a spin transition. Journal of Physical Chemistry C, 2017, 121 (45), pp.25617-25621. ⟨10.1021/acs.jpcc.7b10124⟩. ⟨hal-01946384⟩