نتایج جستجو برای: insulating r
تعداد نتایج: 454968 فیلتر نتایج به سال:
Band theory predicts both K3C60 and K4C60 to be metals; various experimental probes show that while K3C60 is indeed metallic, K4C60 appears to be insulating. The standard view of this apparent failure of the single-particle picture is that electron correlation is predominant. We describe an alternative scenario, motivated on theoretical grounds, which invokes a spinor charge-density-wave state ...
We examine critical properties of the quarter-filled one-dimensional Hubbard model with dimerization and with the onsite and nearest-neighbor Coulomb repulsion U and V . By utilizing the bosonization method, it is shown that the system exhibits an Ising quantum phase transition from the Mott insulating state to the chargeordered insulating state. It is also shown that the dielectric permittivit...
The Mercury Laser Altimeter (MLA) measured surface reflectance, rs, at 1064 nm. On Mercury, most water-ice deposits have anomalously low rs values indicative of an insulating layer beneath which ice is buried. Previous detections of surface water ice (without an insulating layer) were limited to seven possible craters. Here we map rs in three additional permanently shadowed craters that host ra...
To establish fast, nondestructive, and inexpensive methods for resistivity measurements of SiC wafers, different resistivity-measurement techniques were tested for characterization of semi-insulating SiC wafers, namely, the four-point probe method with removable graphite contacts, the van der Pauw method with annealed metal and diffused contacts, the current-voltage (I-V) technique, and the con...
Controlling the dissociation of single water molecule on an insulating surface plays a crucial role in many catalytic reactions. In this work, we have identified the enhanced chemical reactivity of ultrathin MgO(100) films deposited on Mo(100) substrate that causes water dissociation. We reveal that the ability to split water on insulating surface closely depends on the lattice mismatch between...
We report a first-order phase transition at TM=357 K in single crystal Ca2RuO4, an isomorph to the superconductor Sr2RuO4. The discontinuous decrease in electrical resistivity signals the near d e struction of the Mott insulating phase and is triggered by a s t ructural transition from the low temperature orthorhombic to a high temperature tetragonal phase. The magnetic susceptibility, which is...
A (LaVO3)6/(SrVO3)3 superlattice is studied with a combination of sub-Å resolved scanning transmission electron microscopy and monochromated electron energy-loss spectroscopy. The V oxidation state is mapped with atomic spatial resolution enabling us to investigate electronic reconstruction at the LaVO3/SrVO3 interfaces. Surprisingly, asymmetric charge distribution is found at adjacent chemical...
X-ray absorption spectroscopy studies of the magnetic-insulating ground state of Sr2IrO4 at ambient pressure show a clear deviation from a strong spin-orbit (SO) limit J(eff)=1/2 state, a result of local exchange interactions and a nonzero tetragonal crystal field mixing SO split J(eff)=1/2, 3/2 states. X-ray magnetic circular dichroism measurements in a diamond anvil cell show a magnetic trans...
Iron-based superconductivity develops near an antiferromagnetic order and out of a bad-metal normal state, which has been interpreted as originating from a proximate Mott transition. Whether an actual Mott insulator can be realized in the phase diagram of the iron pnictides remains an open question. Here we use transport, transmission electron microscopy, X-ray absorption spectroscopy, resonant...
Sr Cu O ladder compounds contain linear frag ments of copper oxide planes In contrast to the two dimensional antiferromagnetic cuprates the spin two leg ladders have short range magnetic order and a spin gap Holes doped into these ladders pair and superconduct at high doping concentrations while insulators are known to result from low hole concen trations The competition between insulating stat...
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