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Recent scanning tunneling microscopy in the superconducting regime of two different cuprate families has revealed unidirectional bond-centered modulation in the local electronic density of states. Motivated by this result we investigate the…
The recently discovered charge order is a generic feature of cuprate superconductors, however, its microscopic origin remains debated. Within the framework of the fermion-spin theory, the nature of charge order in the pseudogap phase and…
Understanding the electron pairing in hole-doped cuprate superconductors has been a challenge, in particular because the "normal" state from which it evolves is unprecedented. Now, after three and a half decades of research, involving a…
In the past several years, we have developed a theory for the underdoped cuprates in collaboration with X.-G. Wen, based on an SU(2) formulation of the t-J model. In this formulation, the staggered flux state plays a central role as the…
During the last decade, translational and rotational symmetry-breaking phases -- density wave order and electronic nematicity -- have been established as generic and distinct features of many correlated electron systems, including pnictide…
Centrosymmetric multiband superconductors which break time-reversal symmetry generically have two-dimensional nodes, i.e., Fermi surfaces of Bogoliubov quasiparticles. We show that the coupling of the electrons to the lattice always leads…
One of the main challenges in understanding high TC superconductivity is to disentangle the rich variety of states of matter that may coexist, cooperate, or compete with d-wave superconductivity. At center stage is the pseudogap phase,…
The interplay of nearly degenerate orders in quantum materials can lead to a myriad of emergent phases. A prominent case is that of the high-Tc cuprates for which the relationship between superconductivity and a short-ranged, incommensurate…
We investigate the microscopic origin of the pseudogap in the weakly doped 2D Hubbard model using Quantum Monte Carlo within the dynamical cluster approximation. We compare our results with proposed scenarios for the pseudogap. All our…
A Hubbard model at half-filling on an anisotropic triangular lattice has been proposed as the minimal model to describe conducting layers of $\kappa-(BEDT-TTF)_2X$ organic materials. The model interpolates between the square lattice and…
One of the most puzzling facts about cuprate high-temperature superconductors in the lightly doped regime is the coexistence of uniform superconductivity and/or antiferromagnetism with many low-energy charge-ordered states in a…
A symmetry-based interpretation of published experimental results demonstrates that the pseudo-gap phase of underdoped HgBa2CuO4(Hg1201) possesses an ordered state of magnetic charge epitomized by Cu magnetic monopoles. Magnetic properties…
The microscopic origin of the pseudogap state which exists in the underdoped cuprates remains unknown. The $c$-axis properties in the pseudogap regime are particularly anomalous. We use a recently proposed model of a $d$-density wave which…
We study current-current correlations in the three-band Hubbard model for two-leg CuO ladders using the density-matrix renormalization group method. We find that these correlations decrease exponentially with distance for low doping but as…
We find a strongly enhanced entanglement within the pseudogap regime of the Hubbard model. This entanglement is estimated from the quantum Fisher information and, avoiding the ill-conditioned analytical continuation, the quantum variance.…
The pseudogap is a key property of the cuprate superconductors, whose understanding should illuminate the pairing mechanism. Recent experimental data support a close connection between the pseudogap and an oxygen-driven C4 symmetry breaking…
There are processes in nature that resemble a true force but arise due to the minimization of the local energy. The most well-known case is the exchange interaction that leads to magnetic order in some materials. We discovered a new similar…
Upon introducing charge carriers into the copper-oxygen sheets of the enigmatic lamellar cuprates the ground state evolves from an insulator into a superconductor, and eventually into a seemingly conventional metal (a Fermi liquid). Much…
We study the phase fluctuations in the normal state of generic two-dimensional superconducting systems with s-wave pairing. The effect of phase fluctuations of the pairing fields can be dealt with perturbatively using disorder averaging,…
IIn the pseudogap regime of the cuprates, charge order breaks a $\mathbb{Z}_{2}$ symmetry. Therefore, the interaction of charge order and quenched disorder due to potential scattering, can, in principle, be treated as a random field Ising…