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 [1]. We also find that the coexisting incommensurate (smectic) electronic modulations couple to the intra-unit-cell nematicity through their 2π topological defects [2].