Two-dimensional ferroelectricity probed by SHG in ferroelectric LB monolayers

Summary form only given. The nonlinear optical properties of ferroelectric PVDF/TrFE monolayer LB films are studied in the vicinity of phase transitions. A broad hysteresis loop in the SHG intensity under heating and consequent cooling is observed in the temperature range from 0/spl deg/C to 50/spl deg/C. It is found that the main contribution to the nonlinear optical response of PVDF/TrFE LB films originates from the fluctuations of the nonlinear polarisation in the inhomogeneous film structure. These fluctuations are attributed to the complicated polydomain structure of the ferroelectric phase and coexistence of ferroelectric and paraelectric phases in the vicinity of the ferroelectric phase transition.