Optical Second Harmonic Generation Microscopy for Ferroic Materials

Highest-Tc single-component homochiral organic ferroelectrics

“…Second-harmonic generation (SHG) is an effective tool to investigate the phase transitions involving the non-centrosymmetric phase and detect the crystal symmetry change. 48 As demonstrated in Fig. 5a , temperature-dependent SHG signal response measurements for R -CSAI and S -CSAI were carried out.…”

Toroidal Order in Magnetic Metamaterials

“…Furthermore, the coupling of measurable properties to the toroidisation in a material is of rather subtle nature. Therefore, a suitable measurement technique possibly requires an indirect sensing of the spin-driven change in crystal symmetry or a coupling to the order parameter via optical second-harmonic generation (SHG) microscopy [119][120][121][122][123] , a measurement of the magnetic order via spherical neutron polarimetry [124][125][126][127] and X-ray gyrotropy or dichroism 113,128,129 or magnetoelectric measurements 22,26 . Crystals of LiCoPO 4 exhibit long-range toroidal order in their low temperature phase below a temperature of 21.8 K 24,25 .…”

Scientific Background

“…Furthermore, the coupling of measurable properties to the toroidisation in a material is of rather subtle nature. Therefore, a suitable measurement technique possibly requires an indirect sensing of the spin-driven change in crystal symmetry or a coupling to the order parameter via optical second-harmonic generation (SHG) microscopy [88][89][90][91][92], a measurement of the magnetic order via spherical neutron polarimetry [93][94][95][96] and x-ray gyrotropy or dichroism [82,97,98] or magnetoelectric measurements [43,99]. Crystals of LiCoPO 4 exhibit long-range toroidal order in their low temperature phase below a temperature of 21.8 K [29,100].…”