相关论文: Doping-dependent competition between superconducti…
Doping of strongly layered ionic oxides is an established paradigm for creating novel electronic behavior. This is nowhere more apparent than in superconductivity, where doping gives rise to high temperature superconductivity in cuprates…
A series of layered CeO$_{1-x}$F$_x$FeAs compounds with x=0 to 0.20 are synthesized by solid state reaction method. Similar to the LaOFeAs, the pure CeOFeAs shows a strong resistivity anomaly near 145 K, which was ascribed to the…
The in-plane penetration depth of Sr$_{0.88}$La$_{0.12}$CuO$_{2+x}$ thin films at various doping obtained from oxygen reduction has been measured, using AC susceptibility measurements. For the higher doping samples, the superfluid density…
We report the realization of superconductivity by an isovalent doping with phosphorus in LaFeAsO. X-ray diffraction shows that, with the partial substitution of P for As, the Fe$_2$As$_2$ layers are squeezed while the La$_2$O$_2$ layers are…
The in-plane London penetration depth, $\Delta\lambda(T)$, was measured using a tunnel diode resonator technique in single crystals of Ba$_{1-x}$K$_{x}$Fe$_{2}$As$_{2}$ with doping levels $x$ ranging from heavily underdoped, $x$=0.16…
The resistivity, magnetoresistance, and magnetic susceptibility are measured in single crystals of FeTe0.65Se0.35 with Cu, Ni, and Co substitutions for Fe. The crystals are grown by Bridgman's method. The resistivity measurements show that…
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 effect of proximity to a Mott insulating phase on the charge transport properties of a superconductor is determined. An action describing the low energy physics is formulated and different scenarios for the approach to the Mott phase…
High-temperature superconductivity emerges in the CuO$_2$ plane upon doping a Mott insulator. To ascertain the influence of Mott physics plus short-range correlations, we solve a three-band copper-oxide model in the charge-transfer regime…
We present the ab-plane optical conductivity of four single crystals of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ (Bi2212) with different carrier doping levels from the strongly underdoped to the strongly overdoped range with $T_c$=66, 88,…
Using a doping-determined multiband model spectrum of a "typical'' cuprate the effective mass of the paired carriers is calculated on the whole doping scale. Large $m_{ab}$ values quench rapidly with leaving the very underdoped region.…
We have investigated the pressure dependence of the superconducting transition temperature $T_{c}$ up to 18 GPa of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ single crystals ranging from the highly underdoped through the nearly optimally…
We report on the interplay of localized and extended degrees of freedom in the metallic state of high-temperature superconductors in a multiband setting. Various ways in which the bare magnetic response may become incommensurate are…
We measured the terahertz (THz) complex conductivity of Ca doped YBa_{2}Cu_{3}O_{7-\delta} thin films in the frequency range of 0.1 to 3 THz (3 to 100 cm^{-1}) and at a temperature range of 20 to 300 K. The films were measured using both…
The phase diagram of the t-J-V model is discussed using a 1/N expansion in terms of X operators. It is shown that a flux phase of d-wave symmetry is stabilized by the Coulomb interaction V at intermediate dopings and competes with d-wave…
Polycrystalline samples of underdoped (Ba1-xKx)Fe2As2 (x<=0.4) were synthesized and studied by x-ray powder diffraction, magnetic susceptibility, specific heat and 57Fe-Moessbauer-spectroscopy. The structural phase transition from…
We measure and analyze the resistivity of $Bi_2Sr_2CaCu_2O_{8+\delta}$ crystals for different doping $\delta$. We obtain the fraction of carrier $\eta(T,\delta) = n_g/n_{TOT}$ that do not participate to the c-axis conductivity. All the…
Cooperation and competition between the antiferromagnetic, d-wave superconducting and Mott-insulating states are explored for the two-dimensional Hubbard model including nearest and next-nearest-neighbor hoppings at zero temperature. Using…
The effect of Pd doping on the superconducting phase diagram of the unconventional superconductor UPt3 has been measured by (magneto)resistance, specific heat, thermal expansion and magnetostriction. Experiments on single- and…
Using first principle calculations, we examine the sequence of phases in electron doped dichalcogenides, such as recently realized in field-gated MoS$_2$. Upon increasing the electron doping level, we observe a succession of semiconducting,…