Robust superconductivity and the suppression of charge-density wave in the quasi-skutteruditesCa3(Ir1-xRhx)4Sn13single crystals at ambient pressure.

Single crystals of the quasi-skutterudite compounds Ca(IrRh)Sn(3-4-13) were synthesized by flux growth and characterized by x-ray diffraction, energy dispersive x-ray spectroscopy, magnetization, resistivity, and radio frequency magnetic susceptibility techniques. The coexistence and competition between the charge density wave (CDW) and superconductivity was studied by varying the Rh/Ir ratio. The superconducting transition temperature,Tc, varies from 7 K in pure Ir ( = 0) to 8.

Ion-Selective Scattering Studied Using the Variable-Energy Electron Irradiation in the BaKFeAs Superconductor.

Low-temperature variable-energy electron irradiation was used to induce non-magnetic disorder in a single crystal of a hole-doped iron-based superconductor, Ba1-xKxFe2As2, = 0.80. To avoid systematic errors, the beam energy was adjusted non-consequently for five values between 1.

Possible unconventional order parameter in single crystals of SrPtP superconductor.

Anisotropic properties of single crystals of SrPtP were studied using London penetration depth and electrical resistivity measurements. The upper critical field,Hc2(T), was determined from four-probe electrical resistivity measurements for three orthogonal directions of a magnetic field with respect to the crystal. The London penetration depth,λ(T), was determined from the magnetic susceptibility of the Meissner-London state measured using a tunnel-diode resonator technique.

High-Frequency ac Susceptibility of Iron-Based Superconductors.

A microwave technique suitable for investigating the AC magnetic susceptibility of small samples in the GHz frequency range is presented. The method-which is based on the use of a coplanar waveguide resonator, within the resonator perturbation approach-allows one to obtain the absolute value of the complex susceptibility, from which the penetration depth and the superfluid density can be determined. We report on the characterization of several iron-based superconducting systems, belonging to the 11, 122, 1144, and 12442 families.

Topological magnetic hysteresis in single crystals of CeAgSbferromagnet.

Closed-topology magnetic domains are usually observed in thin films and in an applied magnetic field. Here we report the observation of rectangular cross-section tubular ferromagnetic domains in thick single crystals of CeAgSbin zero applied field. Relatively low exchange energy, small net magnetic moment, and anisotropic in-plane crystal electric fields lower the domain wall energy and allow for the formation of the closed-topology patterns.