Two routes to disorder-induced magnetism and nematicity in the cuprates

We study disorder-induced magnetism within the Gutzwiller approximation applied to the t-J model relevant for cuprate superconductors. We identify two distinct disorder-induced magnetic phases depending on the strength of the scatterers. For weak potential scatterers, charge reorganization may push local regions in-between the impurities across the magnetic phase boundary, whereas for strong scatterers a local static magnetic moment is formed around each impurity. We calculate the density of states and find a universal low-energy behavior independent of both disorder and magnetization. However, the magnetic regions are characterized by larger (reduced) superconducting gap (coherence peaks) [1]. Recent studies have highlighted the role of a electronic nematic liquid underdoped cuprates. We calculate the spin susceptibility with a small explicitly broken rotational symmetry to show how the induced spin response asymmetry is enhanced by correlations. In the disorder-induced stripe phase, impurities become spin nematogens with a C2 symmetric impurity resonance state, and the disorder-averaged spin susceptibility remains only C2 symmetric at low energies, similar to recent data from neutron scattering on underdoped YBCO [2].\\[4pt] [1] R. B. Christensen et al., accepted Phys. Rev. B (2011).\\[0pt] [2] B. M. Andersen et al., submitted to EPL (2011).