Unified electronic phase diagram for hole-doped high-Tc cuprates

We have analyzed various characteristic temperatures and energies of hole-doped high-Tc cuprates as a function of a dimensionless hole-doping concentration (pu). Entirely based on the experimental grounds we construct a unified electronic phase diagram (UEPD), where three characteristic temperatures (T*'s) and their corresponding energies (E*'s) converge as pu increases in the underdoped regime. T*'s and E*'s merge together with the Tc curve and 3.5kBTc curve at pu - 1.1 in the overdoped regime, respectively. They finally go to zero at pu - 1.3. The UEPD follows an asymmetric half-dome-shaped Tc curve in which Tc appears at pu - 0.4, reaches a maximum at pu - 1, and rapidly goes to zero at pu - 1.3. The asymmetric half-dome-shaped Tc curve is at odds with the well-known symmetric superconducting dome for La2-xSrxCuO4 (SrD-La214), in which two characteristic temperatures and energies converge as pu increases and merge together at pu - 1.6, where Tc goes to zero. The UEPD clearly shows that pseudogap phase precedes and coexists with high temperature superconductivity in the underdoped and overdoped regimes, respectively. It is also clearly seen that the upper limit of high-Tc cuprate physics ends at a hole concentration that equals to 1.3 times the optimal doping concentration for almost all high-Tc cuprate materials, and 1.6 times the optimal doping concentration for the SrD-La214. Our analysis strongly suggests that pseudogap is a precursor of high-Tc superconductivity, the observed quantum critical point inside the superconducting dome may be related to the end point of UEPD, and the normal state of the underdoped and overdoped high temperature superconductors cannot be regarded as a conventional Fermi liquid phase.Comment: 17 pages, 8 figures, and 10 tables. Accepted for the publication of the Physical review

Incoherent non-Fermi liquid scattering in a Kondo lattice

One of the most notorious non-Fermi liquid properties of both archetypal heavy-fermion systems [1-4] and the high-Tc copper oxide superconductors [5] is an electrical resistivity that evolves linearly with temperature, T. In the heavy-fermion superconductor CeCoIn5 [5], this linear behaviour was one of the first indications of the presence of a zero-temperature instability, or quantum critical point. Here, we report the observation of a unique control parameter of T-linear scattering in CeCoIn5, found through systematic chemical substitutions of both magnetic and non-magnetic rare-earth, R, ions into the Ce sub-lattice. We find that the evolution of inelastic scattering in Ce1-xRxCoIn5 is strongly dependent on the f-electron configuration of the R ion, whereas two other key properties -- Cooper-pair breaking and Kondo-lattice coherence -- are not. Thus, T-linear resistivity in CeCoIn5 is intimately related to the nature of incoherent scattering centers in the Kondo lattice, which provides insight into the anomalous scattering rate synonymous with quantum criticality [7].Comment: 4 pages, 3 figures (published version

Can We Really Prevent Suicide?

Every year, suicide is among the top 20 leading causes of death globally for all ages. Unfortunately, suicide is difficult to prevent, in large part because the prevalence of risk factors is high among the general population. In this review, clinical and psychological risk factors are examined and methods for suicide prevention are discussed. Prevention strategies found to be effective in suicide prevention include means restriction, responsible media coverage, and general public education, as well identification methods such as screening, gatekeeper training, and primary care physician education. Although the treatment for preventing suicide is difficult, follow-up that includes pharmacotherapy, psychotherapy, or both may be useful. However, prevention methods cannot be restricted to the individual. Community, social, and policy interventions will also be essentia

Intrinsic electronic superconducting phases at 60 K and 90 K in double-layer Yba_2Cu_3O<6+δ>

Honma, T. ; Hor, P. H., Physical Review B, 75-1, 012508, 2007. "Copyright (2007) by the American Physical Society." publisherWe study superconducting transition temperature (T_c) of oxygen-doped double-layer high-temperature superconductors YBa_2Cu_3O (0≤δ≤1) as a function of the oxygen dopant concentration (δ) and planar hole-doping concentration (P_). We find that T_c, while clearly influenced by the development of the chain ordering as seen in the T_c vs plot, lies on a universal curve originating at the critical hole concentration (P_c)=1/16 in the T_c vs P_ plot. Our analysis suggests that the universal behavior of T_c(P_) can be understood in terms of the competition and collaboration of chemical phases and electronic phases that exist in the system. We conclude that the global superconductivity behavior of Yba_2Cu_3O as a function of doping is electronically driven and dictated by pristine electronic phases at magic doping numbers that follow the hierarchical order based on P_c, such as 2×P_c, 3×P_c, and 4×P_c. We find that there are at least two intrinsic electronic superconducting phases of T_c=60 K at 2×P_c=1/8 and T_c=90 K at 3×P_c=3/16

Universal optimal hole-doping concentration in single-layer high-temperature cuprate superconductors

http://www.iop.org/EJ/abstract/0953-2048/19/9/004 | http://www.iop.org/EJ/abstract/0953-2048/19/9/00

Pseudogap and superconductivity on a common scale of hole concentration for high-Tc superconductors

authorRoom-temperature thermoelectric power S^290 as a function of hole concentration per planer Cu atom (P_pl) has been studied in a chain-free double-layer Y_1−_xCa_xBa_2Cu_3O_6. S^290(P_pl) of Y_1−_xCa_xBa_2Cu_3O_6 (P_pl=x/2) behaves identically to that of single-layer La_2−_xSr_xCuO_4 (P_pl=x). In order to show the validity of the present scale of S^290(P_pl), we demonstrate the phase diagram for bilayer Yba_2Cu_3O_y system and Bi_2Sr_2CaCu_2O_y system and discuss

Pseudogap and superconductivity on a common scale of hole concentration for high-Tc superconductors

http://www.sciencedirect.com/science/journal/09214534 | http://www.sciencedirect.com/science/journal/0921453