Related papers: Nematic fluctuations and their wave vector in two-…
Many correlated materials display a quantum critical point between a paramagnetic and a SDW state. The SDW wave vector connects points (hot spots) on opposite sides of the Fermi surface. The Fermi velocities at these pairs of points are in…
In this work we revisit itinerant ferromagnetism in 2D and 3D electron gases with arbitrary spin-orbit splitting and strong electron-electron interaction. We identify the resonant scattering processes close to the Fermi surface that are…
We have calculated the one-electron susceptibility of hydrated NaxCoO2 and find strong nesting nearly commensurate with a 2X2 superstructure. The nesting involves about 70% of all electrons at the Fermi level and is robust with respect to…
Correlation effects in CuO$_2$ layers give rise to a complicated landscape of collective excitations in high-T$_{\rm c}$ cuprates. Their description requires an accurate account for electronic fluctuations at a very broad energy range and…
We study charge ordered solutions for fermions on a square lattice interacting with dynamic antiferromagnetic fluctuations. Our approach is based on real space Eliashberg equations which are solved self-consistently. We first show that the…
The electronic nematic phase is an unconventional state of matter that spontaneously breaks the rotational symmetry of electrons. In iron-pnictides/chalcogenides and cuprates, the nematic ordering and fluctuations have been suggested to…
The electronic nematic phase occurs when the point-group symmetry of the lattice structure is broken, due to electron-electron interactions. We study a model for the nematic phase on a square lattice with emphasis on the phase transition…
Realizing topological semimetal states with novel emergent fermions in magnetic materials is a focus of current research. Based on first-principle calculations and symmetry analysis, we reveal interesting magnetic emergent fermions in an…
Isoelectronic substitution is an ideal tuning parameter to alter electronic states and correlations in iron-based superconductors. As this substitution takes place outside the conducting Fe planes, the electronic behaviour is less affected…
Near a quantum-critical point, a metal reveals two competing tendencies: destruction of fermionic coherence and attraction in one or more pairing channels. We analyze the competition within Eliashberg theory for a class of quantum-critical…
In elemental Bismuth, 10$^5$ atoms share a single itinerant electron. Therefore, a moderate magnetic field can confine electrons to the lowest Landau level. We report on the first study of metallic thermoelectricity in this regime. The main…
The Peierls instability in multi-channel metal nanowires is investigated. Hyperscaling relations are established for the finite-size-, temperature-, and wavevector-scaling of the electronic free energy. It is shown that the softening of…
Quasi-two dimensional itinerant fermions in the Anti-Ferro-Magnetic (AFM) quantum-critical region of their phase diagram, such as in the Fe-based superconductors or in some of the heavy-fermion compounds, exhibit a resistivity varying…
Resistivity measurements were performed for the itinerant Ising-type ferromagnet URhAl at temperatures down to 40 mK under high pressure up to 7.5 GPa, using single crystals. We found that the critical pressure of the Curie temperature…
By means of high-resolution angle resolved photoelectron spectroscopy (ARPES) we have studied the fermiology of 2H transition metal dichalcogenide polytypes TaSe2, NbSe2, and Cu0.2NbS2. The tight-binding model of the electronic structure,…
Neutron scattering is used to probe magnetic excitations in FeSe_{0.4}Te_{0.6} (T_c=14 K). Low energy spin fluctuations are found with a characteristic wave vector $(0.5,0.5,L)$ that corresponds to Fermi surface nesting and differs from…
Whether the pairing mechanism for superconductivity in iron-based superconductors is of itinerant or local character is a question still debated on. In order to investigate the influence of Fermi surface nesting, we calculate from…
High-temperature superconductivity occurs near antiferromagnetic instabilities and nematic state. Debate remains on the origin of nematic order in FeSe and its relation with superconductivity. Here, we use transport, neutron scatter- ing…
We present a combined analysis of neutron scattering and photoemission measurements on superconducting FeSe(0.5)Te(0.5). The low-energy magnetic excitations disperse only in the direction transverse to the characteristic wave vector…
We have studied the magnetic excitations in Ca$_{2-x}$Sr$_x$RuO$_4$, x=0.52 and 0.62, which exhibit an anomalous high susceptibility and heavy mass Fermi liquid behavior. Our inelastic neutron scattering experiments reveal strongly enhanced…