Superconductivity in high-entropy alloy system containing Th.

Th-containing superconducting high entropy system with the nominal composition (NbTa)[Formula: see text](MoWTh)[Formula: see text] was synthesized. Its structural and physical properties were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, specific heat, resistivity and magnetic measurements. Two main phases of alloy were observed: major bcc structure and minor fcc.

Point-contact spectroscopy of heavy fermion superconductors CePdInand CePdInin comparison with CeCoIn.

We report point-contact spectroscopy measurements on heavy fermion cousins CeCoIn, CePdInand CePdInto systematically study the hybridization betweenand conduction electrons. Below a temperature*, the spectrum of each compound exhibits an evolving Fano-like conductance shape, superimposed on a sloping background, that suggests the development of hybridization between localand itinerant conduction electrons in the coherent heavy fermion state below*. We present a quantitative analysis of the conductance curves with a two-channel model to compare the tunneling process between normal metallic silver particles in our soft point-contact and heavy-fermion single crystals CeCoIn, CePdInand CePdIn.

Antiferromagnetic Ordering and Transport Anomalies in Single-Crystalline CeAgAs.

Single crystals of the ternary cerium arsenide CeAgAs were grown by chemical vapor transport. They were studied by means of x-ray diffraction, magnetization, heat capacity and electrical transport measurements. The experimental research was supplemented with electronic band structure calculations.

Magnetic field-driven quantum criticality in antiferromagnetic CePtIn.

Physics of the quantum critical point is one of the most perplexing topics in current condensed-matter physics. Its conclusive understanding is forestalled by the scarcity of experimental systems displaying novel aspects of quantum criticality. We present comprehensive experimental evidence of a magnetic field-tuned tricritical point separating paramagnetic, antiferromagnetic, and metamagnetic phases in the compound CePtIn Analyzing field variations of its magnetic susceptibility, magnetoresistance, and specific heat at very low temperatures, we trace modifications of the antiferromagnetic structure of the compound.

Magnetic field driven complex phase diagram of antiferromagnetic heavy-fermion superconductor CePtIn.

We present the results of our comprehensive investigation on the antiferromagnetic heavy-fermion superconductor CePtIn carried out by means of electrical transport, heat capacity and ac magnetic susceptibility measurements, performed on single-crystalline specimens down to 50 mK in external magnetic fields up to 9 T. Our experimental results elucidate a complex magnetic field - temperature phase diagram which contains both first- and second-order field-induced magnetic transitions and highlights the emergence of field stabilized phases. Remarkably, a prominent metamagnetic transition was found to occur at low temperatures and strong magnetic fields.

Interplay of atomic randomness and Kondo effect in disordered metallic conductor La2NiSi3.

A polycrystalline sample of La2NiSi3 was investigated by means of heat capacity, magnetic susceptibility, magnetization, electrical resistivity and magnetoresistivity measurements. The compound was basically characterized as a Pauli paramagnet with metallic-like electrical conductivity, notably reduced in magnitude and weakly temperature dependent, as is usually observed for atomically disordered systems. Furthermore, the experimental data revealed the presence of a small amount of paramagnetic impurities.

CePd2Al2, CePd3Al3, and CePd4Al4-A new homologous series built of CaBe2Ge2- and CsCl-type units.

The aluminides CePd2Al2, CePd3Al3, and CePd4Al4 were synthesized and their properties studied by X-ray diffraction, magnetic, heat capacity, and electrical transport measurements. The crystal structures of CePd2Al2 and CePd4Al4 were determined and refined from the single-crystal X-ray diffraction data, while that of CePd3Al3 was designed by the trial-and-error method on the basis of crystal chemistry considerations and refined by the Rietveld method from the X-ray powder diffraction data. All three compounds were found to crystallize in the tetragonal space group P4/nmm with Z = 2.

Magnetism and weak electronic correlations in Ce₂PdGa₁₂.

Single crystals of Ce2PdGa12 were studied by means of specific heat and electrical transport measurements, performed in wide ranges of temperature and magnetic field strength. The results corroborate the antiferromagnetic ordering reported in the literature, yet seem to exclude the heavy-fermion nature of the compound that has been previously suggested. The derived magnetic phase diagram involves a tricritical point that separates the phase boundaries of second- and first-order character.

Metamagnetism in CePd5Ge3.

Metamagnetic transitions in CePd5Ge3 were investigated by means of low-temperature magnetization, magnetic susceptibility, electrical resistivity and magnetoresistivity measurements. In transverse magnetic fields applied in a direction close to the b-axis the antiferromagnetic structure of the compound undergoes two successive transitions, first to a spin-flop phase and then to a paramagnetic phase with field-induced ferromagnetic-like alignment of the Ce magnetic moments. In contrast, a single anomaly occurs in the magnetic field dependences of the resistivity in a transverse magnetic field applied close to the c-axis, which reflects a direct transition from antiferromagnetic to paramagnetic state.

Anomalous superfluid density in quantum critical superconductors.

When a second-order magnetic phase transition is tuned to zero temperature by a nonthermal parameter, quantum fluctuations are critically enhanced, often leading to the emergence of unconventional superconductivity. In these "quantum critical" superconductors it has been widely reported that the normal-state properties above the superconducting transition temperature T(c) often exhibit anomalous non-Fermi liquid behaviors and enhanced electron correlations. However, the effect of these strong critical fluctuations on the superconducting condensate below T(c) is less well established.