Dynamical Susceptibility in KH_2PO_4-type Crystals above and below T_c : Condensed Matter: Structure, etc.

概要

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The time dependent cluster approximation called the path probability method (PPM) is applied to a pseudo-spin Ising Hamiltonian of the Slater-Takagi model for KH_2PO_4-type hydrogen-bonded ferroelectrics in order to calculate the homogeneous dynamical susceptibility χ(ω) above and below the ferroelectric transition temperature T_c. Above the transition temperature all the calculations are carried out analytically in the cactus approximation of the PPM. Below the transition temperature the dynamical susceptibility is also calculated accurately since the analytical solution of spontaneous polarization in the ferroelectric phase can be utilized. When the temperature is approached from both sides of the transition temperature, only one of relaxation times shows a critical slowing down and makes a main contribution to the dynamical susceptibility. The discrepancy from Slater model (ice-rule limit) is discussed in comparison with some experimental data.
社団法人日本物理学会の論文
2001-04-15