Moessbauer study and nonlinear excitations in the antiferromagnetic chain of rubidium manganese iron fluoride hydrate [Rb2Mn1-xFexF5.cntdot.H2O (x.ltoreq.0.50)

Magnetic Susceptibility Calculated from Correlation-Lengths Derived by Mössbauer Relaxation Spectra

“…The anisotropy constants in Table 2 are to compare with the averaged value D/k = 2.75(3) K derived from Mössbauer spectroscopy (see Figure 3). [8], We want to emphasize that a feature of our experimental results is the observation of two subspectra, each of which shows a separate relaxation mechanism. Approaching the magnetically split phase from above one observes the apparent coexistence of contributions from the paramagnetic and magnetically ordered phase.…”

“…When mixing of the ground and excited states becomes important, the susceptibilities differ from the spin-only prediction and become anisotropic due to the existence of a local anisotropy (zero-field splitting) [8].…”

“…The model given in (1) The characteristic Mössbauer parameters as quadrupole splitting and magnetic hyperfine field H are listed in Table 2 or are given in [6][7][8][9][10][11][12][19][20][21], The detailed theoretical analysis of domain wall dynamics and solitons in magnetic chains with a large local anisotropy D shows that, in a certain range above the critical temperature T N , the density of K domain walls and their motion determines the spin autocorrelation function (5(0)5(0), which is obtained by measuring the fluctuating hyperfine field H(t) ^ 5(f). The temperature dependence of the Mössbauer spectra for a representative powder sample of (NH 4 ) 2 Mn 0 98 Fe 0 02 F 5 (one of ten investigated fluoromanganates(HI) compounds) is shown in Figure 1.…”

“…The activation energy £ A , as determined from the electronic fliprate as a function of inverse temperature (see (8)). was systematically found to be twice the energy £ s of a single soliton.…”

“…Mössbauer effect in the iron-doped compounds of A 2 Mn ()98 Fe 002 F 5 (H 2 O) and AMno.9 8 Fe 0 .o2F 5 (H 2 0) [6][7][8][9][10][11][12], where we investigated the spin-dynamics and non-linear excitations (solitons) in these compounds. From the analysis of Mössbauer relaxation spectra based on the classical soliton model [13][14][15][16][17][18] we were able to determine the activation energy for such a soliton from the temperature dependence of the spin-fluctuation rate in the antiferromagnetic 1-d phase even of powder samples [8-10, 12, 19-21].…”