Hidden Order in the Cuprates

We propose that the enigmatic pseudogap phase of cuprate superconductors is characterized by a hidden broken symmetry of d(x^2-y^2)-type. The transition to this state is rounded by disorder, but in the limit that the disorder is made sufficiently small, the pseudogap crossover should reveal itself to be such a transition. The ordered state breaks time-reversal, translational, and rotational symmetries, but it is invariant under the combination of any two. We discuss these ideas in the context of ten specific experimental properties of the cuprates, and make several predictions, including the existence of an as-yet undetected metal-metal transition under the superconducting dome.Comment: 12 pages of RevTeX, 9 eps figure

Ammonium silicate diagenesis and its influence on the interpretation of fixed-ammonium anomalies as an exploration tool

The study of nitrogen (NH{sub 4}{sup +}) diagenesis associated with hydrocarbon occurrences is intended to aid in predicting favorable areas of petroleum exploration and recovery by establishing a better understanding of the interaction of organic maturation products with clastic sedimentary sequences. This research has indicated that fixed-NH{sub 4} in clays preserves anomalous NH{sub 4}{sup +} abundances, thus recording a significant reaction in the maturation of hydrocarbons which correlates with the oil window. Fixed-NH{sub 4} concentrations are independent of total organic carbon content, but increase with organic maturity in source rocks (up to T{approx}140 C). The authors have found anomalously high fixed-NH{sub 4} concentrations in oil and gas reservoirs, and in sandstones that may have acted as migration conduits for a nearby oilfield. The remainder of the project period will be spent completing publications, and finalizing the interpretation of results on fixed-NH{sub 4} in the Salton Sea (SSDP) and Monterey Fm. The data that authors have collected from these areas will allow them to examine the effect of high temperatures and high-N organic matter (prevalent on the west coast) on levels of NH{sub 4}-fixation. The authors will also develop some preliminary ideas on the mechanism of NH{sub 4}{sup +} oxidation responsible for high-N{sub 2} (gas) reservoirs such as Sorrento Field, Colorado