Condensed Matter Physics, 2007, vol. 10, No. 1(49), p. 79-84, English
DOI:10.5488/CMP.10.1.79

Title: On a correlation between EPR data for SASeD doped with Cr3+ and soft modes
Author(s):
  I.E.Lipinski (Institute of Physics, Szczecin University of Technology, Aleja Piast\'ow 17, 70--310 Szczecin, Poland) ,
  J.Kuriata (Institute of Physics, Szczecin University of Technology, Aleja Piast\'ow 17, 70--310 Szczecin, Poland) ,
  N.A.Korynevskii (Institute of Physics, Szczecin University of Technology, Aleja Piast\'ow 17, 70--310 Szczecin, Poland; Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, Svientsitskii 1., 79011Lviv, Ukraine; Institute of Physics, University of Szczecin, Wielkopolska 15., 70--451 Szczecin, Poland)

PR experimental results obtained for SASeD doped with Cr3+ are reported with special emphasis on those observations which reveal the effect of soft modes i.e. the temperature dependence of the DZZ spin-Hamiltonian parameter and the temperature dependence of the EPR linewidth. An extension of the two-sublattice model, previously developed and tested for SASD, to include lattice vibrations is presented. The obtained spectrum of bound excitations for the system investigated supports the idea that soft modes contribute to the phase transition at TC = 175 K. The anomaly detected at T1 =150 K has only a quasisoft mode character and the anomaly detected at T2 = 280 K cannot be related to the effect of soft modes.

Key words: sodium ammonium selenate dihydrate, EPR, soft modes,phase transitions
PACS: 76.30.K, 77.80.Bh


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