Evidence of intermolecular pi-stacking enhancement of second-harmonic generation in a family of single chain magnets

The second-order nonlinear optical properties of a family of rare-earth-based single chain magnets are presented ( using a fundamental field at wavelength lambda = 766 nm), together with an analysis of the origin of the second-harmonic generation (SHG) process. By studying the fundamental crystal symmetries and the geometrical arrangement of the constituting elements of the system in the unit cell we show that the main contribution to the nonlinear process arises from intermolecular pi-stacking interactions.