AVS 60th International Symposium and Exhibition
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP34
Spin Crossover Transition in a Molecular Adsorbate

Tuesday, October 29, 2013, 6:00 pm, Room Hall B

Session: Surface Science Poster Session
Presenter: X. Zhang, University of Nebraska Lincoln
Authors: X. Zhang, University of Nebraska Lincoln
S. Beniwal, University of Nebraska Lincoln
T. Palamarciuc, Université de Bordeaux, France
P. Rosa, Université de Bordeaux, France
J.F. Létard, Université de Bordeaux, France
J. Liu, Northeastern University
E. Vega Lozada, University of Puerto Rico – Humacao
F. Torres, University of Puerto Rico – Humacao
L.G. Rosa, University of Puerto Rico – Humacao
B. Doudin, Université Louis Pasteur Strasbourg, France
A. Enders, University of Nebraska Lincoln
P.A. Dowben, University of Nebraska Lincoln
Correspondent: Click to Email
We investigated the occupied and unoccupied electronic structure of ultra thin films of the spin crossover [Fe(H2B(pz)2)2(bipy)] complex (with H2B(pz)2= bis(hydrido)bis(1H-pyrazol-1-yl)borate and bipy = 2,2’-bipyridine) by ultraviolet photoelectron spectroscopy (UPS), inverse photoemission (IPES) and X-ray absorption spectroscopy (XAS). The XAS spectra clearly shows the change of iron L edge spectra associated with thermal induced spin crossover and the Raman spectra are consistent with the intact molecule – so the molecule can be evaporated and will form a thin molecule film on a variety of substrates. The shift of the unoccupied density of states seen in inverse photoemission is consistent with the thermally induced spin crossover transition for molecules deposited on the organic ferroelectric copolymer polyvinylidene fluoride with trifluoroethylene (PVDF-TrFE) as well as gold. Perhaps more significant is the fact that the spin crossover transition, and certainly the unoccupied electronic structure, is influenced by the ferroelectric polarization direction of PVDF-TrFE substrates at temperatures in the vicinity of the thermally driven spin cross-over transition, if the [Fe(H2B(pz)2)2(bipy)] complex film is very thin 25 molecular layers or less. Combining the STM studies of different adsorbate coverage with the thickness dependent IPES results of the molecular adsorbate on gold substrates, we understand that the molecular thin film spin-states transition may well be affected by thickness of the film which significantly change the magnetic moment of the thin film based on the SQUID measurements.