Imaging Ferroelastic Domains in LAO/STO Nanostructures using Cryogenic PFM*

LaAlO3 (LAO) and SrTiO3 (STO) nanostructures exhibit a wide range of interesting quantum phenomena, such as superconductivity and a tunable metal-insulator transition, which offers great promise for application toward quantum computation and quantum devices. The pairing "glue" responsible for superconductivity in STO is still debated. STO undergoes a structural phase transition at T=105 K, and there is evidence that ferroelastic domains strongly influence superconductivity in the LAO/STO heterostructures and nanostructures. We use piezoresponse force microscopy (PFM), a non-destructive measurement technique, to spatially map the ferroelastic domain structure in conductive nanostructures created by conductive atomic force microscopy lithography. The experiments are performed below the structural phase transition, enabling a unique identification of ferroelastic domain structures with conductive patterns