Related papers: Mass enhancement in multiple bands approaching opt…
We use scanning tunneling microscopy to investigate the doping dependence of quasiparticle interference (QPI) in NaFe1-xCoxAs iron-based superconductors. The goal is to study the relation between nematic fluctuations and Cooper pairing. In…
In doped SrTiO$_{3}$ superconductivity persists down to an exceptionally low concentration of mobile electrons. This restricts the relevant energy window and possible pairing scenarios. We present a study of quantum oscillations and…
We have systematically studied the nematic fluctuations in the electron-doped iron-based superconductor BaFe$_{2-x}$Ni$_x$As$_2$ by measuring the in-plane resistance change under uniaxial pressure. While the nematic quantum critical point…
The anomalous transport and thermodynamic properties in the quantum-critical region, in the cuprates, and in the quasi-two dimensional Fe-based superconductors and heavy-fermion compounds, have the same temperature dependences. This can…
The topological semimetal YPtBi has attracted considerable attention, owing to its novel superconducting and normal state properties. A strong band inversion from spin-orbit coupling allows the existence of $j=3/2$ quasiparticles near the…
A magnetic order can be completely suppressed at zero temperature($T$), by doping carriers or applying pressure, at a quantum critical point(QCP), around which physical properties change drastically. However, the situation is unclear for an…
Recently proposed scenarios for the cuprates make extensive use of a ``flat'' quasiparticle (q.p.) dispersion and short-range hole-hole interactions in real-space, both caused by antiferromagnetic (AF) correlations. The density of states…
In underdoped YBa$_2$Cu$_3$O$_{6+x}$, there is evidence of a small Fermi surface pocket subject to substantial mass enhancement in the doping regime $ 0.12<p<0.16$. This mass enhancement may vary substantially over the Fermi surface, due to…
The normal-state transport properties of superconducting infinite-layer nickelates are investigated within an interacting three-orbital model. It includes effective Ni-$d_{z^2}$, Ni-$d_{x^2-y^2}$ bands as well as the self-doping band degree…
A scenario is presented, in which the presence of a quantum critical point due to formation of incommensurate charge density waves accounts for the basic features of the high temperature superconducting cuprates, both in the normal and in…
The multiband nature of iron pnictides gives rise to a rich temperature-doping phase diagram of competing orders and a plethora of collective phenomena. At low dopings, the tetragonal-to-orthorhombic structural transition is closely…
Due to their proximity to an antiferromagnetic phase and to the mysterious pseudogap, underdoped cuprates have attracted great interest in the high Tc community for many years. A central issue concerns the role of quantum and thermal…
The quest for high-temperature superconductivity at ambient pressure is a central issue in physics. In this regard, the relationship between unconventional superconductivity and the quantum critical point (QCP) associated with the…
The temperature dependence of the paramagnetic susceptibility of the iron pnictide superconductor KFe2As2 and its connection with the spectral properties of that material is investigated by a combination of density functional theory (DFT)…
The free energy expansion of a two-band pair-transfer superconductor is developed. A critical in temperature and a noncritical coherence length appear. The effective in-plane $\xi_{ab}$, $H_{c2}\sp c\sim \xi_{ab}\sp{-2}$ and the…
A grand challenge in many-body quantum physics is to explain the apparent connection between quantum criticality and high-temperature superconductivity in the cuprates and similar systems, such as the iron pnictides and chalcogenides. Here…
We report systematic Angle Resolved Photoemission (ARPES) experiments using different photon polarizations and experimental geometries and find that the doping evolution of the normal state of Ba(Fe1-xCox)2As2 deviates significantly from…
We study the diamagnetism induced by thermal fluctuations above the superconducting transition of the iron pnictide Ba(Fe$_{1-x}$Ni$_x$)$_2$As$_2$ with different doping levels. The measurements are performed with magnetic fields up to 7 T…
By using a 60 T magnetic field to suppress superconductivity in La2-pSrpCuO4, (LSCO) we reveal an anomalous peak in the Hall number, located at optimum doping and developing at temperatures below the zero-field superconducting transition…
We used angle resolved photoemission spectroscopy and thermoelectric power to study the poorly explored, highly overdoped side of the phase diagram of Ba(Fe1-xCox)2As2 high temperature superconductor. Our data demonstrate that several…