ESR Study of Cr3+ Doped LiNH4C4H4O6·H2O (LAT)

Electron spin resonance experiments of Cr 3+ doped LiNH 4 C 4 H 4 O 6 ·H 2 O ( LAT ) single crystals were carried out. Two kinds of Cr 3+ sites were observed. The spin Hamiltonian parameters in its paraelectric phase were determined as | D |=38.39×10 -3 cm -1 , | E |=3.03×10 -3 cm -1 for A -site and | D |=47.54×10 -3 cm -1 , | E |=5.96×10 -3 cm -1 for B -site The resonance lines split continuously and smoothly just below the transition temperature. These splitting can be reasonably explained by considering the symmetry change associated with the phase transition and the formation of the domains. Electric field and shear stress Z x dependence of ESR lines were measured at a temperature lower than the Curie point, by about 10 K. It was confirmed that the spontaneous polarization can be reversed not only by applying the electric field but also by applying the shear stress Z x . This indicates that LAT is both ferroelectric and ferroelastic below the transition temperature.