Charge 4e4e superconductivity from pair density wave order in certain high temperature superconductors

A number of spectacular experimental anomalies\cite{li-2007,fujita-2005} have recently been discovered in certain cuprates, notably {\LBCO} and {\LNSCO}, which exhibit unidirectional spin and charge order (known as ``stripe order''). We have recently proposed to interpret these observations as evidence for a novel ``striped superconducting'' state, in which the superconducting order parameter is modulated in space, such that its average is precisely zero. Here, we show that thermal melting of the striped superconducting state can lead to a number of unusual phases, of which the most novel is a charge $4e$ superconducting state, with a corresponding fractional flux quantum $hc/4e$. These are never-before observed states of matter, and ones, moreover, that cannot arise from the conventional Bardeen-Cooper-Schrieffer (BCS) mechanism. Thus, direct confirmation of their existence, even in a small subset of the cuprates, could have much broader implications for our understanding of high temperature superconductivity. We propose experiments to observe fractional flux quantization, which thereby could confirm the existence of these states.Comment: 5 pages, 2 figures; new version in Nature Physics format with a discussion of the effective Josephson coupling J2 and minor changes. Mildly edited abstract. v3: corrected versio

Comparative analysis of the binding of thiacalix[4]arene-monocrown-ethers with monovalent metal salts using MALDI mass spectrometry

© 2016, Pleiades Publishing, Ltd.MALDI mass spectrometry is used for the first time for the rapid assessment of the binding of thiacalix[4]arene-monocrown-ethers with metal cations (Li, Na, K, Cs, Cu, Ag). The work is performed on examples of thiacalix[4]arene-monocrown-ethers in 1,3-alternate conformation with various numbers (m) of ethylene oxide units and various substituents in phenol groups. It is shown that thiacalix[4]arene-monocrown- ethers with m = 3, 4, 5, and 6 bind lithium, sodium, potassium, and cesium cations, respectively; in addition, the binding of cesium cations is stronger in the presence of aromatic substituents in the lower rim of thiacalix[4]arene-monocrown-ethers. Silver cations bind with calixarenes under study more intensely than copper ions. When aromatic substituents are present, the binding of silver cations is stronger than that of alkali metal ions with the studied thiacalix[4]arene-monocrown-ethers

The formation of secondary arylphosphines in the reaction of organonickel sigma-complex [NiBr(Mes)(bpy)], where Mes = 2,4,6-trimethylphenyl, bpy = 2,2′-bipyridine, with phenylphosphine

© 2016 Taylor & Francis Group, LLC.The reactivity of organonickel sigma-complex [NiBr(Mes)(bpy)], where Mes = 2,4,6-trimethylphenyl, bpy = 2,2’-bipyridine towards phenylphosphine (PhPH2) has been investigated. It was found that this interaction leads to secondary mesitylphenylphosphine and dimesitylphosphine by formation of new carbon-phosphorus bond involving mesityl fragment of starting organonickel sigma-complex

First example of organonickel complex bearing three cyclic substituents in the σ-bonded aromatic ring: Bromo[(2,2' -bipyridine)-2,4,6-tricyclohexylphenylnickel]

© 2016 Mendeleev Communications. Published by ELSEVIER B.V.The electrochemical reduction of [NiBr2(bpy)] (bpy is 2,2'-bipyridine) complex in the presence of 2,4,6-tricyclohexylphenylbromide (TchpBr) in undivided electrochemical cell supplied with a sacrificial nickel anode results in the one-pot formation of an organonickel complex [NiBr(Tchp)(bpy)] bearing three cyclic substituents in the s-bonded aromatic ring. The synthesized complex was characterized by various methods including single crystal X-ray analysis

Single vortex structure in two models of iron pnictide s±s^\pm superconductivity

The structure of a single vortex in a FeAs superconductor is studied in the framework of two formulations of superconductivity for the recently proposed sign-reversed $s$ wave ($s^\pm$) scenario: {\it (i)} a continuum model taking into account the existence of an electron and a hole band with a repulsive local interaction between the two; {\it (ii)} a lattice tight-binding model with two orbitals per unit cell and a next-nearest-neighbour attractive interaction. In the first model, the local density of states (LDOS) at the vortex centre, as a function of energy, exhibits a peak at the Fermi level, while in the second model such LDOS peak is deviated from the Fermi level and its energy depends on band filling. An impurity located outside the vortex core has little effect on the LDOS peak, but an impurity close to the vortex core can almost suppress it and modify its position.Comment: 17 pages, 15 figures. Accepted for publication in New Journal of Physic

Search for Doubly-Charged Higgs Boson Production at HERA

A search for the single production of doubly-charged Higgs bosons H^{\pm \pm} in ep collisions is presented. The signal is searched for via the Higgs decays into a high mass pair of same charge leptons, one of them being an electron. The analysis uses up to 118 pb^{-1} of ep data collected by the H1 experiment at HERA. No evidence for doubly-charged Higgs production is observed and mass dependent upper limits are derived on the Yukawa couplings h_{el} of the Higgs boson to an electron-lepton pair. Assuming that the doubly-charged Higgs only decays into an electron and a muon via a coupling of electromagnetic strength h_{e \mu} = \sqrt{4 \pi \alpha_{em}} = 0.3, a lower limit of 141 GeV on the H^{\pm\pm} mass is obtained at the 95% confidence level. For a doubly-charged Higgs decaying only into an electron and a tau and a coupling h_{e\tau} = 0.3, masses below 112 GeV are ruled out.Comment: 15 pages, 3 figures, 1 tabl