Berlin 2008 – scientific programme
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MA: Fachverband Magnetismus
MA 32: Postersession II: Spinstruct./Phase Trans. (1-10); Spinelectronics (11-15); Thin Films (16 - 36); Particles/Clusters (37-45); Multiferroics (46-54); Spindynamics/Spin Torque (55 - 76); Post Deadlines (77-79)
MA 32.4: Poster
Friday, February 29, 2008, 11:15–14:00, Poster E
Study of iron spin states in the low dimensional polymeric system PAC by ESR and static magnetometry — •A. Alfonsov1, Ch. Golze1, V. Kataev1, U. Pietsch2, Y. Bodenthin3, G. Schwarz4, D. G. Kurth4, and B. Büchner1 — 1IFW Dresden, Helmholtzstr. 20, 01069 Dresden — 2University of Siegen — 3PSI Villingen, Switzerland — 4MPI-KG Potsdam
Tunable high-field Electron Spin Resonance (ESR) and magnetization measurements were used to determine the presence and the properties of the spin-crossover effect in the iron based polyelectrolyte - amphiphile complex (PAC). This metallosupramolecular complex is the result of a self-assembling process of Fe(II), 1,4-bis(2,2':6',2"-terpyridin-4'-yl)benzene with dihexadecyl phosphate. The magnetically active ion, Fe(II), is sixfold coordinated by nitrogen ions. This pseudo octahedral ligand crystal field (CF) affects the splitting of the 3d-levels of the iron ion. Depending on the strength of the CF, the splitting may give rise to a low spin (LS, S=0) or a high spin (HS, S=2) ground state of Fe. Transitions from LS to HS have been produced by a heat treatment of PAC which is detected by magnetization and ESR measurements of the polycrystalline samples. The transition temperature (380K) was determined by magnetization measurements. Furthermore, in the absorption spectrum of the powder sample a splitting of the main ESR signal into two separate ESR lines has been observed at high frequencies (> 80 GHz), which indicates g-factor anisotropy. We discuss a relationship between the structural transformation and magnetic properties occurring in Fe-PAC samples.