Related papers: Tunable quantum critical point and detached superc…
For both electron- and hole-doped cuprates, superconductivity appears in the vicinity of suppressed broken symmetry order, suggesting that quantum criticality plays a vital role in the physics of these systems. A confounding factor in…
Establishing the presence and the nature of a quantum critical point in their phase diagram is a central enigma of the high-temperature superconducting cuprates. It could explain their pseudogap and strange metal phases, and ultimately…
The ternary iron arsenide BaFe2As2 becomes superconducting by hole doping, which was achieved by partial substitution of the barium site with potassium. We have discovered bulk superconductivity up to Tc = 38 K in (Ba1-xKx)Fe2As2 with x =…
CeRh$_6$Ge$_4$ is unusual in that its ferromagnetic transition can be suppressed continuously to zero temperature, i.e., to a ferromagnetic quantum-critical point (QCP), through the application of modest hydrostatic pressure. This discovery…
In many classes of unconventional superconductors, the question of whether the superconductivity is enhanced by the quantum-critical fluctuations on the verge of an ordered phase remains elusive. One of the most direct ways of addressing…
The evolution of pressure induced superconductivity in single crystal as well as polycrystalline samples of BaFe2As2 has been investigated through temperature dependent electrical resistivity studies in 0-7 GPa pressure range. While the…
The behavior of matter near a quantum critical point (QCP) is one of the most exciting and challenging areas of physics research. Emergent phenomena such as high-temperature superconductivity are linked to the proximity to a QCP. Although…
Superconductivity in doped SrTiO$_3$ has remained an enduring mystery for over 50 years. The material's status as a ``quantum" ferroelectric metal, characterized by a soft polar mode, suggests that quantum criticality could play a pivotal…
We report the 75As nuclear quadrupole resonance (NQR) and specific heat measurements of the heavily hole-doped superconductor KFe2As2 (Tc = 3.5 K). The spin-lattice relaxation rate 1/T1 in the superconducting state exhibits quite gradual…
We study how superconducting Tc is affected as an electronic system in a tetragonal environment is tuned to a nematic quantum critical point (QCP). Including coupling of the electronic nematic variable to the relevant lattice strain…
In rare-earth doped single crystalline CaFe2As2, the mysterious small volume fraction which superconducts up to 49 K, much higher than the bulk Tc ~ 30s K, has prompted a long search for a hidden variable that could enhance the Tc by more…
One of the greatest challenges to Landau's Fermi liquid theory - the standard theory of metals - is presented by complex materials with strong electronic correlations. In these materials, non-Fermi liquid transport and thermodynamic…
By substituting Fe with the 5d-transition metal Pt in BaFe2As2, we have successfully synthesized the superconductors BaFe2-xPtxAs2. The systematic evolution of the lattice constants indicates that the Fe ions were successfully replaced by…
We investigated the elastic properties of the iron-based superconductor Ba(Fe1-xCox)2As2 with eight Co concentrations. The elastic constant C66 shows large elastic softening associated with the structural phase transition. The C66 was…
Quantum ground states on the non-trivial side of a topological quantum critical point (TQCP) have unique properties that make them attractive candidates for quantum information applications. A recent example is provided by s-wave…
We describe the spectral properties of underdoped cuprates as resulting from a momentum-dependent pseudogap in the normal state spectrum. Such a model accounts, within a BCS approach, for the doping dependence of the critical temperature…
Superconductivity in the C32 compounds CaAlSi and SrAlSi is investigated by heat capacity (Cp) measurements as well as high-pressure ac-susceptibility experiments. The heat capacity in the superconducting state is well explained by the BCS…
We have measured the low-energy quasiparticle excitation spectrum of the electron doped high-temperature superconductors (HTS) Nd(1.85)Ce(0.15)CuO(4-y) and Pr(1.85)Ce(0.15)CuO(4-y) as a function of temperature and applied magnetic field…
Non-centrosymmetric superconductors, whose crystal structure is absent of inversion symmetry, have recently received special attentions due to the expectation of unconventional pairings and exotic physics associated with such pairings. The…
The last 15 years have witnessed important progresses in our understanding of the mechanism of superconductivity in the high-$T_{c}$ cuprates. There is now strong evidence that the strange metal behavior is induced by the quantum critical…