Spectroscopic imaging STM studies of broken electronic symmetries in underdoped cuprates
We use spectroscopic imaging scanning tunneling microscopy (SI-STM) to visualize the spatial symmetries of the electronic states that occur at the pseudogap energy scale in underdoped cuprates. We find evidence for the local intra-unit-cell electronic nematicity - by which we mean the disordered breaking of C 4v symmetry within each CuO 2 unit cell . We also find that the coexisting incommensurate (smectic) electronic modulations couple to the intra-unit-cell nematicity through their 2Ï€ topological defects . Â© 2012 Elsevier B.V. All rights reserved.