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Register a new userInfluence of Ni doping on critical parameters of PdTe superconductor
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We report the effect of Ni doping on superconductivity of PdTe. The superconducting parameters like critical temperature (Tc), upper critical field (Hc2) and normalized specific-heat jump are reported for Ni doped Pd1-xNixTe. The samples of series Pd1-xNixTe with nominal compositions x=0, 0.01, 0.05, 0.07, 0.1, 0.15, 0.2, 0.3 and 1.0 are synthesized via vacuum shield solid state reaction route. All the studied samples of Pd1-xNixTe series are crystallized in hexagonal crystal structure as refined by Rietveld method to space group P63/mmc. Both the electrical resistivity and magnetic measurements revealed that Tc decreases with increase of Ni concentration in Pd1-xNixTe. The magneto-transport measurements suggest that flux is better pinned for 20% Ni doped PdTe as compared to other compositions of Pd1-xNixTe. The effect and contribution of Ni 3d electron to electronic structure and density of states near Fermi level in Pd1-xNixTe are also studied using first-principle calculations within spin polarized local density approximation. The overlap of bands at Fermi level for NiTe is larger as compared to PdTe. Also the density of states just below Fermi level (in conduction band) drops much lower for PdTe than as for NiTe. Summarily, Ni doping in Pd1-xNixTe superconductor suppresses superconductivity moderately and also Ni is of non magnetic character in these compounds.
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We report the impact of Ni doping on superconductivity of PdTe superconductor. The superconducting parameters like critical temperature (Tc), upper critical field (Hc2) and normalized specific-heat jump are reported for Ni doped Pd1-xNixTe. The samples of series Pd1-xNixTe with nominal compositions x=0, .01, 0.05, 0.07, 0.1, 0.15, 0.2, 0.3 and 1.0 are synthesized via solid state reaction route. All the studied samples of series Pd1-xNixTe (x = 0.0 to 1.0) are crystallized in hexagonal crystal structure within the space group P63/mmc. Unit cell volume shrinks almost linearly upon Ni doping in Pd1-xNixTe. The normal state residual resistivity increases with Ni substitution on Pd site. Both the electrical resistivity and magnetic measurements revealed that Tc decreases with increase of Ni concentration in Pd1-xNixTe and is not observed down to 2K for x=0.30 i.e., 30% of Ni doping at Pd site. Interestingly, this is unusual for magnetic Ni doping in a known type-II BCS type superconductor. Magnetic Ni must suppress the superconductivity much faster. Interestingly, the isothermal magnetization measurements for NiTe revealed that Ni is non-magnetic in Pd1-xNixTe structure and hence the Tc depression is mainly due to disorder. The magneto-transport measurements revealed that flux is better pinned for 20% Ni doped PdTe as compared to other compositions of Pd1-xNixTe. The magnetic field dependence of specific heat of Pd1-xNixTe for x=0.01 was studied and the estimated value of the normalized specific-heat jump,is found to be 1.42, which is under BCS weak-coupling limit. Summarily, we report the impact of Ni doping in Pd1-xNixTe superconductor and conclude that Ni substitutes at Pd site, suppress superconductivity moderately and is of non magnetic nature in this system. To best of our knowledge this is the first study on Ni substitution in PdTe superconductor.
The Josephson current through a 1D quantum wire with Rashba spin-orbit and electron-electron interactions is calculated. We show that the interplay of Rashba and Zeeman interactions gives rise to a supercurrent through the 1D conductor that is anomalous in the sense that it persists in the absence of any phase difference between the two superconducting leads to which it is attached. The electron dispersion asymmetry induced by the Rashba interaction in a Luttinger-liquid wire plays a significant role for poorly transmitting junctions. It is shown that for a weak or moderate electron-electron interaction the spectrum of plasmonic modes confined to the normal part of the junction becomes quasi-random in the presence of dispersion asymmetry.
A series of 122 phase BaFe$_{2-x}$Ni$_x$As$_2$ ($x$ = 0, 0.055, 0.096, 0.18, 0.23) single crystals were grown by self flux method and a dome-like Ni doping dependence of superconducting transition temperature is discovered. The transition temperature $T_c^{on}$ reaches a maximum of 20.5 K at $x$ = 0.096, and it drops to below 4 K as $x$ $geq$ 0.23. The negative thermopower in the normal state indicates that electron-like charge carrier indeed dominates in this system. This Ni-doped system provides another example of superconductivity induced by electron doping in the 122 phase.
We performed an angle-resolved photoemission spectroscopy study of the Ni-based superconductor SrNi$_2$As$_2$. Electron and hole Fermi surface pockets are observed, but their different shapes and sizes lead to very poor nesting conditions. The experimental electronic band structure of SrNi$_2$As$_2$ is in good agreement with first-principles calculations after a slight renormalization (by a factor 1.1), confirming the picture of Hunds exchange-dominated electronic correlations decreasing with increasing filling of the $3d$ shell in the Fe-, Co- and Ni-based compounds. These findings emphasize the importance of Hunds coupling and $3d$-orbital filling as key tuning parameters of electronic correlations in transition metal pnictides.
In four classes of materials, the layered copper-oxides, organics, iron-pnictides and heavy-fermion compounds, an unconventional superconducting state emerges as a magnetic transition is tuned toward absolute zero temperature, that is, toward a magnetic quantum-critical point (QCP). In most materials, the QCP is accessed by chemical substitutions or applied pressure. CeCoIn5 is one of the few materials that are born as a quantum-critical superconductor and, therefore, offers the opportunity to explore the consequences of chemical disorder. Cadmium-doped crystals of CeCoIn5 are a particularly interesting case where Cd substitution induces long-range magnetic order, as in Zn-doped copper-oxides. Applied pressure globally supresses the Cd-induced magnetic order and restores bulk superconductivity. Here we show, however, that local magnetic correlations, whose spatial extent decreases with applied pressure, persist at the extrapolated QCP. The residual droplets of impurity-induced magnetic moments prevent the reappearance of conventional signatures of quantum criticality, but induce a heterogeneous electronic state. These discoveries show that spin droplets can be a source of electronic heterogeneity in classes of strongly correlated electron systems and emphasize the need for caution when interpreting the effects of tuning a correlated system by chemical substitution.
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