We report angle-resolved photoemission spectroscopy experiments probing deep into the hidden-order state of URu(2)Si(2), utilizing tunable photon energies with sufficient energy and momentum resolution to detect the near Fermi-surface (FS) behavior. Our results reveal (i) the full itinerancy of the 5f electrons, (ii) the crucial three-dimensional k-space nature of the FS and its critical nesting vectors, in good comparison with density-functional theory calculations, and (iii) the existence of hot-spot lines and pairing of states at the FS, leading to FS gapping in the hidden-order phase.

At T0 = 17.5 K an exotic phase emerges from a heavy fermion state in URu2Si2. The nature of this hidden order (HO) phase has so far evaded explanation. Formation of an unknown quasiparticle (QP) structure is believed to be responsible for the massive removal of entropy at HO transition, however, experiments and ab-initio calculations have been unable to reveal the essential character of the QP. Here we use femtosecond pump-probe time-and angle-resolved photoemission spectroscopy (tr-ARPES) to elucidate the ultrafast dynamics of the QP. We show how the Fermi surface is renormalized by shifting states away from the Fermi level at specific locations, characterized by vector q<110> = 0.56 ± 0.08Å −1 . Measurements of the temperature-time response reveal that upon entering the HO the QP lifetime in those locations increases from 42 fs to few hundred fs. The formation of the long-lived QPs is identified here as a principal actor of the HO.Over the last 25 years, the nature of the hidden order transition in a heavy fermion system URu 2 Si 2 has remained a mystery. The sharp second-order transition at T 0 = 17.5 K [1-13], marked by a large jump in specific heat, corresponds to removal of more than 10 percent of total entropy [14]. The phase transition might have been consistent with magnetism, but several years of intensive search showed the absence of magnetism in HO phase. Antiferromagnetism is observed only under pressure [15]. Partial gapping of the Fermi surface was proposed in the context of itinerant models [8,9,11,12] and the HO gap was shown to behave similarly to a BCS order parameter [16]. Entropy removal at HO transition also suggested that the Fermi surface instability induces reconstruction of the density of states. It was proposed that a commensurate [6,9,10,17,18] or incommensurate [4,11,12] renormalization of the Fermi surface is the driver of HO transition, with magnetic fluctuations[9] or hybridization wave [11,12] as mechanisms for the gap formation. However, the underlying physics behind the key QPs, the gap formation, symmetry, and momentumdependence remain elusive, in spite of several models of HO proposed over the years [4, 7-10, 12, 17, 18].The picture of HO is also obscured by the formation of a hybridization gap, a typical feature of heavy fermion materials [19]. Such a gap formation is due to hybridization of the flat f-band with a strongly dispersive d-band, as evidenced by numerous experiments [1-3, 14, 20, 21].The hybridization gap onset is related to the coherence temperature T*, usually from 60 K to 100 K for uraniumbased heavy fermion materials [22] and estimated at 70 K in URu 2 Si 2 . At T 0 the stage is already set by a well established f-d hybridization gap structure evolving in a mean-field behavior [23,24]. To reveal the nature of the HO transition within the hybridization gap, one needs to track the QPs responsible for the Fermi surface renormalization. Several recent investigations using ARPES, INS and Scanning Tunneling Microscopy (STM) demonstrate that the HO transition is mark...

The Rhyparochromidae, the largest family of Lygaeoidea, encompasses more than 1,850 described species, but no mitochondrial genome has been sequenced to date. Here we describe the first mitochondrial genome for Rhyparochromidae: a complete mitochondrial genome of Panaorus albomaculatus (Scott, 1874). This mitochondrial genome is comprised of 16,345 bp, and contains the expected 37 genes and control region. The majority of the control region is made up of a large tandem-repeat region, which has a novel pattern not previously observed in other insects. The tandem-repeats region of P. albomaculatus consists of 53 tandem duplications (including one partial repeat), which is the largest number of tandem repeats among all the known insect mitochondrial genomes. Slipped-strand mispairing during replication is likely to have generated this novel pattern of tandem repeats. Comparative analysis of tRNA gene families in sequenced Pentatomomorpha and Lygaeoidea species shows that the pattern of nucleotide conservation is markedly higher on the J-strand. Phylogenetic reconstruction based on mitochondrial genomes suggests that Rhyparochromidae is not the sister group to all the remaining Lygaeoidea, and supports the monophyly of Lygaeoidea.

In order to probe the magnetic ground state, we have carried out temperature dependent magnetic Compton scattering experiments on an oriented single crystal of magnetite (Fe3O4), together with the corresponding first-principles band theory computations to gain insight into the measurements. An accurate value of the magnetic moment µS associated with unpaired spins is obtained directly over the temperature range of 10-300K. µS is found to be non-integral and to display an anomalous behavior with the direction of the external magnetic field near the Verwey transition. These results reveal how the magnetic properties enter the Verwey energy scale via spin-orbit coupling and the geometrical frustration of the spinel structure, even though the Curie temperature of magnetite is in excess of 800 K. The anisotropy of the magnetic Compton profiles increases through the Verwey temperature Tv and indicates that magnetic electrons in the ground state of magnetite become delocalized on Fe B-sites above Tv.