Observation of spontaneously grown domain structure in SBO crystals via nonlinear diffraction

Partially ordered domain structure is detected for the first time in non-ferroelectric strontium tetraborate crystal via nonlinear diffraction. Domains have the form of sheets with the domain walls oriented perpendicularly to the α crystallographic axis. The thickness of domains is the random quantity; the spatial Fourier spectrum of the nonlinear susceptibility protrudes from π/6 to π/0.2 μm-1.