SPIN-LATTICE RELAXATION BY THE DIRECT PROCESS OF Fe3+ IN POTASSIUM COBALTICYANIDE

1966 ◽  
Vol 44 (12) ◽  
pp. 3185-3196
Author(s):  
C. F. Weissfloch
Keyword(s):  
Magnetic Field ◽  
Relaxation Time ◽  
Point Charge ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Potassium Ferricyanide ◽  
Spin Lattice Relaxation ◽  
Direct Process ◽  
Spin Lattice ◽  
Satisfactory Prediction

The spin-lattice relaxation time of dilute potassium ferricyanide was measured as a function of the orientation of the static magnetic field in three orthogonal planes at 9.4 GHz and 1.75 °K.A calculation of the spin-phonon Hamiltonian applicable to the case of three Kramer doublets degenerate with respect to the cubic component of the crystalline bond is given. The theory was applied to the ferricyanide on the basis of Van Vleck's point-charge model.Despite the fact that the ferricyanide complex is known to be considerably covalent, it is found that the theory gives a satisfactory prediction of the observed angular dependence.

SPIN–LATTICE RELAXATION TIME OF Fe3+ ION

1964 ◽  
Vol 42 (4) ◽  
pp. 583-594 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Relaxation Time ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Direct Process ◽  
Phonon Interaction ◽  
Crystal Axis ◽  
Spin Lattice Relaxation Time ◽  
Spin Lattice ◽  
Relaxation Effects

The spin–lattice relaxation time T1 of Fe3+ ions in iron–rubidium alum [RbAl(SO4)2∙12H2O], in rutile [TiO2], and in potassium cobalticyanide [K3CO(CN)6] has been measured in the temperature range 1.6 °K to 4.2 °K at a frequency of 9400 Mc by the pulse saturation technique. For Fe3+ in rubidium alum, it is found that for crystals having a nominal concentration of 1% and lower the variation of relaxation time with temperature is of the form [Formula: see text]; for higher concentrations the variation is of the form [Formula: see text]. Cross-relaxation effects are noticed for higher concentrations at all settings of crystal orientations. For Fe3+ in rutile on the average, the relaxation time is approximately inversely proportional to temperature, thus indicating the presence of a direct process. There is no significant change in the relaxation time, when the angle of the applied magnetic field with the crystal axis is varied. For Fe3+in K3Co(CN)6, above 2.8 °K, it is found that the relaxation time is proportional to T−8; this is consistent with a two-phonon interaction process (Raman). It is not believed that at the lowest temperature used in this experiment relaxation is taking place through a single-phonon process (direct).

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