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Structural and electronic properties of Sr RuO /Sr Ru O heterostructures
Full text linkWe carry out first-principles calculations for Sr2RuO4/Sr3Ru2O7 superlattices. We show that such systems develop a significant structural rearrangement within the superlattice, which leads to a modification of the electronic structure close to the Fermi level. Compared with the pure Sr2RuO4 and Sr3Ru2O7 phases, we find that the positions of the peaks in the density of states close to the Fermi levels get shifted and renormalized in the spectral weight. Then, by means of the maximally localized Wannier functions approach, we determine the effective tight-binding parameters for Ru bands and used them to discuss the modification of the electronic structure and the collective behavior of superlattice with respect to the bulk phases
Edge States and Topological Insulating Phases Generated by Curving a Nanowire with Rashba Spin-Orbit Coupling
Full text linkWe prove that curvature effects in low-dimensional nanomaterials can promote the generation of topological states of matter by considering the paradigmatic example of quantum wires with Rashba spin-orbit coupling, which are bent in a nanoscale periodic serpentine structure. The effect of the periodic curvature generally results in the appearance of insulating phases with a corresponding novel butterfly spectrum characterized by the formation of finite measure complex regions of forbidden energies. When the Fermi energy lies in the gaps, the system displays localized end states protected by topology. We further show that for certain superstructure periods the system possesses topologically nontrivial insulating phases at half filling. Our results suggest that the local curvature and the topology of the electronic states are inextricably intertwined in geometrically deformed nanomaterials
Application of the global SO(4) symmetry in the diagonalization of translationally invariant correlated electron models
No full textWe present a method for the simultaneous implementation of the spin symmetry, the pseudospin symmetry and the translational invariance in models for correlated electron systems on finite-size clusters. The application of this method leads to a significative reduction of the size of the Hamiltonian matrix blocks, thus considerably simplifying the diagonalization procedure. We illustrate the method solving exactly the Hubbard model on a 8-site chain in the Hilbert subspaces labelled by the eigenvalues of the spin, the pseudospin and the momentum operators. Some relevant thermodynamical quantities, such as the specific heat and the static magnetic susceptibility, are then evaluated and a brief discussion on the tendency of the model to exhibit ferromagnetism is also presented
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