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MA: Magnetismus
MA 14: Poster: Schichten(1-31), Spinabh.Trsp.(32-47), Exch.Bias(48-54), Spindyn.(55-64), Mikromag.(65-76), Partikel(77-88), Oflmag.(89-92), Spinelektr.(93-98), Elektr.Theo.(99-103), Mikromag+PhasÜ+Aniso.(104-122), MagnMat.(123-134), Messm+Mol-Mag.(135-139), Kondo(140-151)
MA 14.148: Poster
Tuesday, March 25, 2003, 15:15–19:15, Zelt
Structural and magnetic properties of the alternating Heisenberg spin-chain compound dichloro(2,5-dithiahexane)copper(II) — •S. Matejcek1, E. Herrling1, G. Fischer1, B. Pilawa1, and H. Henke2 — 1Physikaliches Institut, Universität Karlsruhe (TH), 76128 Karlsruhe, Germany — 2Institut für Anorganische Chemie, Universität Karlsruhe (TH), 76128 Karlsruhe, Germany
The one-dimensional alternating Heisenberg antiferromagnet
dichloro(2,5-dithiahexane)copper(II)
shows a structural phase transition at Tc≈150K. This phase
transition was examined by
ESR-measurements, x-ray diffraction, measurements of the static magnetic
susceptibility and the specific
heat. Below Tc the symmetry reduction from the monoclinic space group
P21/n to the
triclinic group P1 results in the formation of twin domains and the
creation of
two different kinds of spin chains. Measurements of the static magnetic
susceptibility yield
the exchange constants and alternation parameters J1/kB=−29.3K,
α1=0.76 and
J2/kB=−27.9K, α2=0.99 of chain 1 and 2, respectively.
The specific heat was measured in the temperature range between 10K and
200K using the method
of continuous heating. The hysteretic behaviour of the phase transition was
studied by
measurements using different heating rates. The transition enthalpy of the
structural
phase transition was determined and it was proved that the low temperature
phase is
stable with no further phase transitions down to 10K.