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Finding new pairing mechanism for heavy fermion superconductivity |
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2018.07.10
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In heavy fermion superconductors, the effective mass of normal state heavy electrons can reach hundreds of times that of a free electron. Accordingly, the characteristic Fermi energy is reduced to the order of meV. Thus the discovery of heavy fermion superconductivity in CeCu2Si2 by German scientist Frank Steglich in 1979 had two major consequences. First, the transition temperature (0.6 K) reaches 5% of the Fermi energy, much higher than that of elemental superconductors, which may be viewed as “high temperature superconductivity”. Second, its Debye temperature is about 20 times the Fermi energy, which falls out of the paradigm of the w...
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Scientists produced ultrahigh-charge relativistic electron beams in laser-solid interaction |
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2018.07.10
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Compact acceleration of a tightly collimated relativistic electron beam with high charge from a laser-plasma interaction has many unique applications. However, currently the well-known schemes, including laser wakefield acceleration from gases and vacuum laser acceleration from solids, often produce electron beams either with low charge or with large divergence angles. In this work, we report the generation of highly collimated electron beams with a divergence angle of a few degrees, nonthermal spectra peaked at the megaelectronvolt level, and extremely high charge (～100 nC) via a powerful subpicosecond laser pulse inter- acting with a so...
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Charge-Carrier Dynamics Determine Perovskite Photovoltaics |
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2018.04.28
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The photovoltaic performance of the perovskite solar cell is determined by the charge-carrier dynamics. These fundamental properties and dynamics behaviors have been discussed and presented to provide a comprehensive understanding into the optoelectronic physics of the perovskite material and devices
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Universal Scaling of Intrinsic Resistivity in Two-Dimensional Metallic Borophene |
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2018.03.30
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The resistivity of metals originating from electron-phonon (e-ph) interactions (i.e. their intrinsic resistivity ρe-ph) is an important fundamental quantity in condensed matter physics and materials science. Recently, several borophene phases have been synthesized on Ag surfaces, e.g., β12, χ3 and triangle sheets (Nat. Chem. 2016, 8 (6), 563-568; Science 2015, 350, 1513). All experimentally realized borophenes exhibit intrinsic metallic properties, providing an ideal platform to explore the transport properties of two-dimensional (2D) metals.
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Magnon Valve Effect Between Two Magnetic Insulators |
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2018.03.19
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The key physics of the spin valve involves spin-polarized conduction electrons propagating between two magnetic layers such that the device conductance is controlled by the relative magnetization orientation of two magnetic layers. Here, we report the effect of a magnon valve which is made of two ferromagnetic insulators (YIG) separated by a nonmagnetic spacer layer (Au). When a thermal gradient is applied perpendicular to the layers, the inverse spin Hall voltage output detected by a Pt bar placed on top of the magnon valve depends on the relative orientation of the magnetization of two YIG layers, indicating the magnon current induced by...
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