The discovery of new high temperature superconductivity at the beginning of March this year, generated tremendous interest in condensed matter community, and a flurry of recent experimental and theoretical activity. Exciting applications to superconducting cables, were recently demonstrated.
In our recent preprint (Correlated electronic structure of LaOFeAs) , we were the first to point out that phonons can not explain high superconducting transition temperatures found in the iron oxypnictides. We predicted the band structure and optical conductivity of the correlated metal, LaOFeAs, the parent compound of the new high-Tc's.
In the second preprint (Coherence-incoherence crossover in the normal state of iron-oxypnictides and importance of the Hund's rule coupling) we addressed the normal state properties of the doped compound, and explained where do the magnetic moments come from, and why is the material correlated. We predicted resistivity, magnetic susceptibility, and specific heat of the doped compound. The Hund's coupling was estimated to be 0.35-0.4eV.
Here are some links to hot papers on FeAs superconductors .  

In this Science report we address the fundamental question of crossover from localized to itinerant state of a paradigmatic heavy fermion material CeIrIn₅. The temperature evolution of the one electron spectra and the optical conductivity is predicted from first principles calculation. The buildup of coherence in the form of a dispersive many body feature is followed in detail and its effects on the conduction electrons of the material is revealed. We find multiple hybridization gaps and link them to the crystal structure of the material. Our theoretical approach explains the multiple peak structures observed in optical experiments and the sensitivity of CeIrIn₅ to substitutions of the transition metal element and may provide a microscopic basis for the more phenomenological descriptions currently used to interpret experiments in heavy fermion systems.  

Online article coverage:

Science 318, 1618 (2007); 10.1126/science.1149064 (Science Express Reports) (November 1 2007)

    Perspective , Report

In this Nature letter, we explain the unique nature of plutonium delta phase, namely its mixed valence nature, and contrast it to curium metallic phase where f electrons are localized and order antiferromagneticaly at low temperature. Curium follows americium in periodic table and is thus kind of analog of plutonium: plutonium has one hole in americium inert f-shell (J=0) while curium has one more electron in the americium inert shell. The striking different properties of the two elements (one mixed valent non magnetic and other magnetic with Tc=65K) was hard to understand with any band structure method. We developed accurate Dynamical Mean-Field Method in combination with LDA and showed that it describes from first principles the peculiarities of the two materials. This method is the first that described magnetism at finite temperature from first principles and show that plutonium is non-magnetic while curium orders below 100K. This method holds a great promise that it could predict magnetism from first principles.  

 

Online article coverage:

Nature 446, 513-516 (29 March 2007)

    News&Views , Letter ,& Supplementary Information .