Superconductivity in doped Weyl semimetal Mo0.9IR0.1Te2 with broken inversion symmetry

This work presents the emergence of superconductivity in Ir - doped Weyl semimetal T$_d$ - MoTe$_{2}$ with broken inversion symmetry. Chiral anomaly induced planar Hall effect and anisotropic magneto-resistance confirm the topological semimetallic nature of Mo$_{1-x}$Ir$_{x}$Te$_{2}$. Observation of weak anisotropic, moderately coupled type-II superconductivity in T$_d$ -Mo$_{1-x}$Ir$_{x}$Te$_{2}$ makes it a promising candidate for topological superconductor.

The Magnetization of a Composite Based on Reduced Graphene Oxide and Polystyrene

The use of reduced graphene oxide (r-GO) is a promising way of fabricating organic–inorganic composites with unique electrical and magnetic properties. In our work, polystyrene/r-GO composites were synthesized, in which both the components are linked together by covalent bonds. The r-GO used differs from the graphene obtained from graphite through mechanical exfoliation using the ‘scotch tape’ by presenting many structural defects. Binding in the composite structure between the components was confirmed by infrared spectroscopy. Elemental analysis was carried out by energy dispersive X-ray spectroscopy. Scanning electron microscopy, X-ray diffraction, and Raman spectroscopy were used to monitor the 2D-order in exfoliated r-GO galleries. Using a vibrating-sample magnetometer, we have shown that the composite magnetization loops demonstrate type-II superconductivity up to room temperature due to r-GO flakes. We believe that a strain field in the r-GO flakes covalently binding to a polymeric matrix is responsible for the superconductivity phenomena.

Synthesis PbFCl-Type Mixed Anion APX(A=Hf, X=S, Se) Superconductors Related with Topological Materials by High-Pressure Technique

We performed a systematic study of the crystal structure, physical properties, and electronic structure of PbFCl-type intermetallic APX(A=Zr, Hf, X=S and Se) superconductor. We successfully synthesized single-phase polycrystalline samples for the Se substitution range of 0.4≤x≤0.8 in Zr(P2-xSex) using high pressure technique. On the other hand, S substitution range in Zr(P2-xSx) was narrow of 0.4≤x≤0.6, the S substitution range in Hf(P2-xSx) was narrow of x≈0.55, and the Se substitution range in Hf(P2-xSex) was also very narrow of x≈0.4. Zr(P2-xSex) exhibits a dome-like superconducting phase diagram for the substitution amount x. The superconducting transition temperature (Tc) is achieved at approximately x≈0.75 at which point the Tcis 6.3 K for Zr(P1.25Se0.75), 5.5 K for Hf(P1.30Se0.70), 5.0 K for Zr(P1.325S0.675), and 4.6 K for Hf(P1.50S0.50), respectively. Tcfor Zr(P1.25Se0.75) is increased from 6.3 K to 7.6 K by partially substituting a non-magnetic rare earth Sc atom for Zr. Single crystals of Zr(P1.25Se0.75) and partially substituted by Sc atom for Zr site of the ZrP2-xSexwere also grain grown using high pressure technique. Plate-like single crystal with approximate edge sizes of up to 500 × 300 × 20 μm3for (Zr0.50Sc0.50)PSe nominal composition was obtained. Tc= 8.36 K was reached and the Hc1//c-axis(0) and Hc1⊥c-axis(0) roughly determined are 0.0045 T and 0.0038 T, respectively. Assuming the type-II superconductivity in dirty limit, the Hc2//c-axis(0) value of 1.33 T was also obtained. In this presentation, the crystal growth and physical properties of this APX(A=Zr, Hf, X=S and Se) superconductor has reported.

The Path to Type-II Superconductivity

Following the discovery of superconductivity by Heike Kamerlingh Onnes in 1911, research concentrated on the electric conductivity of the materials investigated. Then, it was Max von Laue who in the early 1930s turned his attention to the magnetic properties of superconductors, such as their demagnetizing effects in a weak magnetic field. As a consultant at the Physikalisch-Technische Reichsanstalt in Berlin, von Laue was in close contact with Walther Meissner at the Reichsanstalt. In 1933, Meisner together with Robert Ochsenfeld discovered the perfect diamagnetism of superconductors (Meissner–Ochsenfeld effect). This was a turning point, indicating that superconductivity represents a thermodynamic equilibrium state and leading to the London theory and the Ginzburg–Landau theory. In the early 1950s in Moscow, Nikolay Zavaritzkii carried out experiments on superconducting thin films. In the theoretical analysis of his experiments, he collaborated with Alexei A. Abrikosov and for the first time they considered the possibility that the coherence length ξ can be smaller than the magnetic penetration depth λ m . They called these materials the “second group”. Subsequently, Abrikosov discovered the famous Abrikosov vortex lattice and the superconducting mixed state. The important new field of type-II superconductivity was born.