Cuprate universal electronic spin response and the pseudogap from NMR

High-temperature superconductivity, in particular in the cuprates, is central to condensed matter physics, and telltale experimental laws for guiding theory are desirable. Here we report on such a universal property from the linear response of the electronic matter to a homogeneous static magnetic field. From it, two different types of carriers are identified. The universal behavior concerns the carriers from hybridized copper and oxygen orbitals that span the defining element, the CuO$_2$ plane, of the superconducting cuprates. Their spin response is similar to that of a material independent metallic density of states which carries a temperature independent, but doping dependent pseudogap that closes beyond optimal doping. The second electronic spin component has a strong family and doping dependent density of states, and it involves only Cu (isotropic orbitals, except for \lsco). The condensation of both types of carriers is interconnected and sets the critical temperature of superconductivity ($T_\mathrm{c}$). The inter-planar component can condense at the same or lower temperatures compared to that of the planar component, and a certain match in density of states seems to be required for the highest $T_\mathrm{c}$. The second component reminds one of the proposed involvement of another Cu axial orbital that relates to the distance or presence of the apical oxygen \cite{Ohta1991,Pavarini2001,Mahony2022} and the charge distribution in the CuO$_2$ plane \cite{Kowalski2021,Jurkutat2023}, which correlates with the maximum $T_\mathrm{c}$, as well.Comment: 7 pages, 5 figure

Temperature-Independent Cuprate Pseudogap from Planar Oxygen NMR

Planar oxygen nuclear magnetic resonance (NMR) relaxation and shift data from all cuprate superconductors available in the literature are analyzed. They reveal a temperature-independent pseudogap at the Fermi surface, which increases with decreasing doping in family-specific ways, i.e., for some materials, the pseudogap is substantial at optimal doping while for others it is nearly closed at optimal doping. The states above the pseudogap, or in its absence are similar for all cuprates and doping levels, and Fermi liquid-like. If the pseudogap is assumed exponential it can be as large as about 1500 K for the most underdoped systems, relating it to the exchange coupling. The pseudogap can vary substantially throughout a material, being the cause of cuprate inhomogeneity in terms of charge and spin, so consequences for the NMR analyses are discussed. This pseudogap appears to be in agreement with the specific heat data measured for the YBaCuO family of materials, long ago. Nuclear relaxation and shift show deviations from this scenario near Tc, possibly due to other in-gap states

Planar Cu and O NMR and the Pseudogap of Cuprate Superconductors

Recently, an analysis of all available planar oxygen shift and relaxation data for the cuprate high-temperature superconductors showed that the data can be understood with a simple spin susceptibility from a metallic density of states common to all cuprates. It carries a doping dependent but temperature independent pseudogap at the Fermi surface, which causes the deviations from normal metallic behavior, also in the specific heat. Here, a more coherent, unbiased assessment of all data, including planar Cu, is presented and consequences are discussed, since the planar Cu data were collected and analyzed prior to the O data. The main finding is that the planar Cu shifts for one direction of the external magnetic field largely follow from the same states and pseudogap. This explains the shift suppression stated more recently, which leads to the failure of the Korringa relation in contrast to an enhancement of the relaxation due to antiferromagnetic spin fluctuations originally proposed. However, there is still the need for a second spin component that appears to be associated with the Cu 3(2−2) hole to explain the complex Cu shift anisotropy and family dependence. Furthermore, it is argued that the planar Cu relaxation which was reported recently to be rather ubiquitous for the cuprates, must be related to this universal density of states and the second spin component, while not being affected by the simple pseudogap. Thus, while this universal metallic density of states with a pseudogap is also found in the planar Cu data, there is still need for a more elaborate scenario that eludes planar O

Temperature-Independent Cuprate Pseudogap from Planar Oxygen NMR

Planar oxygen nuclear magnetic resonance (NMR) relaxation and shift data from all cuprate superconductors available in the literature are analyzed. They reveal a temperature-independent pseudogap at the Fermi surface, which increases with decreasing doping in family-specific ways, i.e., for some materials, the pseudogap is substantial at optimal doping while for others it is nearly closed at optimal doping. The states above the pseudogap, or in its absence are similar for all cuprates and doping levels, and Fermi liquid-like. If the pseudogap is assumed exponential it can be as large as about 1500 K for the most underdoped systems, relating it to the exchange coupling. The pseudogap can vary substantially throughout a material, being the cause of cuprate inhomogeneity in terms of charge and spin, so consequences for the NMR analyses are discussed. This pseudogap appears to be in agreement with the specific heat data measured for the YBaCuO family of materials, long ago. Nuclear relaxation and shift show deviations from this scenario near Tc, possibly due to other in-gap states

Temperature-Independent Cuprate Pseudogap from Planar Oxygen NMR

Planar oxygen nuclear magnetic resonance (NMR) relaxation and shift data from all cuprate superconductors available in the literature are analyzed. They reveal a temperature-independent pseudogap at the Fermi surface, which increases with decreasing doping in family-specific ways, i.e., for some materials, the pseudogap is substantial at optimal doping while for others it is nearly closed at optimal doping. The states above the pseudogap, or in its absence are similar for all cuprates and doping levels, and Fermi liquid-like. If the pseudogap is assumed exponential it can be as large as about 1500 K for the most underdoped systems, relating it to the exchange coupling. The pseudogap can vary substantially throughout a material, being the cause of cuprate inhomogeneity in terms of charge and spin, so consequences for the NMR analyses are discussed. This pseudogap appears to be in agreement with the specific heat data measured for the YBaCuO family of materials, long ago. Nuclear relaxation and shift show deviations from this scenario near Tc, possibly due to other in-gap states

Social Aspects of Water Supply Management in Jordan

Countries in the Middle East have been experiencing severe water shortages for several decades. In Jordan this crisis has been aggravated by population increase, climate change and the influx of Syrian refugees. In the process of managing the increasing water demand and its unstable supply some population groups become disadvantaged. It is increasingly recognised that a sustainable solution to the problem should extend beyond its technical dimension and ensure the involvement of various stakeholder groups. But how can an inclusive participatory process be designed that is likely to arrive at sustainable water management system? This is the question addressed by this book. The potential of participation in water management is examined for three exemplary refugee-hosting Jordanian rural communities. The book goes beyond the discussion of advantages of the approach and determines the conditions under which a participatory process will need to be designed. These are rooted, among other things, in the strong informal institutions regulating relationships within Jordanian society. Making explicit the complex web of water-related interests, social rules and power relations among water users and managers as well as actors’ existing problem-solving capacities is the basis for subsequently elaborating design principles for a participatory process that may lead to a more inclusive and sustainable water management system in the region. Results highlight the need to embed interventions in natural resource management - with tech-nical and institutional components - within the overall social system that forms Jordanian society. This study therefore contributes to the small but growing body of literature on social water stud-ies in the MENA region