Interlayer tunneling resistivity is used to probe the low-energy density-of-states (DOS) depletion due to the pseudogap in the normal state of Bi2Sr2CaCu2O8+y. Measurements up to 60 T reveal that a field that restores DOS to its ungapped state shows strikingly different temperature and doping dependencies from the characteristic fields of the superconducting state. The pseudogap closing field and the pseudogap temperature T ⋆ evaluated independently are related through a simple Zeeman energy scaling. These findings indicate a predominant role of spins over the orbital effects in the formation of the pseudogap.PACS numbers: 74.25. Dw, 74.25.Fy, 74.50.+r, 74.72.Hs A central unresolved issue of high temperature superconductivity is the connection of normal state correlations, referred to as the pseudogap [1][2][3][4][5], to the origins of high-T c . At the heart of the debate [6-11] is whether the pseudogap, which manifests itself as a depletion of the quasiparticle density of states (DOS) below a characteristic temperature T ⋆ , originates from spin or charge degrees of freedom and, in particular, whether it derives from some precursor of Cooper pairing [12] that acquires the superconducting coherence at T c . Energies of the order of the pseudogap have been accessed with elevated temperatures, with applied voltage in tunneling measurements, and with infrared frequencies in optical spectra [1]. But little is known about the effect of magnetic field. The magnetic field response may be unique: e.g., in the case of the superconducting state the upper critical field H c2 is determined by the superconducting coherence length, and not directly by the superconducting gap, since magnetic field strongly couples to the orbital motion of Cooper pairs.Current knowledge about the field dependence of the pseudogap derived from spectroscopic measurements is partly limited by the available dc field range [7][8][9][10][11]. More importantly, there is no systematic doping dependence in a single family of cuprates. Even in optimally doped YBa 2 Cu 3 O 7−δ alone, based on NMR relaxation rate measurements below 27.3 T, the pseudogap was claimed to decrease [7] or be independent of magnetic field [8]. In the underdoped YBa 2 Cu 4 O 8 no field effect on T ⋆ was reported up to 23.2 T [9], while a recent NMR study indicated a measurable field dependence in slightly overdoped TlSr 2 CaCu 2 O 6.8 [10]. In this paper, we report the interlayer (c-axis) resistivity ρ c measurements in fields up to 60 T in Bi 2 Sr 2 CaCu 2 O 8+y (BSCCO) crystals in a wide range of doping, from which we make a first systematic evaluation of the pseudogap closing field H pg that restores DOS to its ungapped state. Our results indicate a pronounced difference between field-temperature (H-T ) diagrams of the pseudogap and the superconducting states and a simple Zeeman scaling between H pg (0) and T ⋆ . Among various techniques that quantify DOS, the ρ c measurements are uniquely suited for exploring the highest magnetic field range available only in a pulsed mod...
The greatest strength of the LA-ICP-MS technique is its application to microsampling in which extremely small pits are obtained. The results of this study highlight some significant different laserinduced fractionations between widely used external reference materials NIST SRM 610-614 and natural silicate reference materials (e.g., USGS reference glasses (GSE-1G, GSD-1G), MPI-DING glasses, USGS basalt glasses and zircon reference material GJ-1) at high spatial resolution analysis. For the sample matrices and analytical conditions used in this study, the laser-induced elemental fractionations for 63 selected isotopes are negligible at the spot sizes of 160-44 mm. However, the laserinduced elemental fractionations of Li, Na, Si, K, V, Cr, Mn, Fe, Co, Ni, Cu, Rb, Cs and U (with respect to Ca) increase significantly with decreasing spot sizes from 44 mm to 32 mm, 24 mm and 16 mm in these natural silicate reference materials. Unlike in these sample matrices, laser-induced elemental fractionations of these elements in NIST SRM 610-614 are unique in that they are almost not affected by the change of spot sizes from 44 to 32 to 24 mm, with only slight increase at the spot sizes of 16 mm. The much less significant laser-induced elemental fractionation in NIST SRM 61X in comparison with other natural silicate materials makes them not ideal as external reference materials at high spatial resolution analysis. Alternatively, this NIST SRM 61X-specific matrix effect for Li, Na, K, V, Cr, Mn, Fe, Co, Ni, Cu, Rb, Cs and U can be minimized by using Si for internal standardization. U and Pb in zircon GJ-1 are exceptions, which are zircon-specific.
The TianQin-1 satellite (TQ-1), which is the first technology demonstration satellite for the TianQin project, was launched on
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