Following the discovery of superconductivity in quasi-one-dimensional K2Cr3As3 containing [(Cr3As3) 2− ]∞ chains [J. K. Bao et al., arXiv: 1412.0067 (2014], we succeeded in synthesizing an analogous compound, Rb2Cr3As3, which also crystallizes in a hexagonal lattice. The replacement of K by Rb results in an expansion of a axis by 3%, indicating a weaker interchain coupling in Rb2Cr3As3. Bulk superconductivity emerges at 4.8 K, above which the normal-state resistivity shows a linear temperature dependence up to 35 K. The estimated upper critical field at zero temperature exceeds the Pauli paramagnetic limit by a factor of two. Furthermore, the electronic specific-heat coefficient extrapolated to zero temperature in the mixed state increases with √ H, suggesting existence of nodes in the superconducting energy gap. Hence Rb2Cr3As3 manifests itself as another example of unconventional superconductor in the Cr3As3-chain based system.

We report the discovery of bulk superconductivity (SC) at 6.1 K in a quasi-one-dimensional (Q1D) chromium pnictide K2Cr3As3 which contains [(Cr3As3) 2− ]∞ double-walled subnano-tubes with face-sharing Cr 6/2 (As 6/2 ) octahedron linear chains in the inner (outer) wall. The material has a large electronic specific-heat coefficient of 70∼75 mJ K −2 mol −1 , indicating significantly strong electron correlations. Signature of non-Fermi liquid behavior is shown by the linear temperature dependence of resistivity in a broad temperature range from 7 to 300 K. Unconventional SC is preliminarily manifested by the estimated upper critical field exceeding the Pauli limit by a factor of three to four. The title compound represents a rare example that possibly unconventional SC emerges in a Q1D system with strong electron correlations.

Superconductivity (SC) and charge-density wave (CDW) are two contrasting yet relevant collective electronic states which have received sustained interest for decades. Here we report that, in a layered europium bismuth sulfofluoride, EuBiS2F, a CDW-like transition occurs at 280 K, below which SC emerges at 0.3 K, without any extrinsic doping. The Eu ions were found to exhibit an anomalously temperature-independent mixed valence of about +2.2, associated with the formation of CDW. The mixed valence of Eu gives rise to self electron doping into the conduction bands mainly consisting of the in-plane Bi-6p states, which in turn brings about the CDW and SC. In particular, the electronic specific-heat coefficient is enhanced by ∼ 50 times, owing to the significant hybridizations between Eu-4f and Bi-6p electrons, as verified by band-structure calculations. Thus, EuBiS2F manifests itself as an unprecedented material that simultaneously accommodates SC, CDW and f -electron valence instability.

We employ NMR techniques to investigate the nature of Mn spins in the I-II-V diluted magnetic semiconductor Li(Zn1−xMnx)P (x = 0.1, Curie temperature Tc = 25 K). We successfully identify the 7 Li NMR signals arising from the Li sites adjacent to Mn 2+ , and probe the static and dynamic properties of Mn spins. From the NMR spin-lattice relaxation data, we show that the Mn spin-spin interactions extend over many unit cells.

Superconductivity in low-dimensional compounds has long attracted much interest. Here we report superconductivity in a low-dimensional ternary telluride Ta4Pd3Te16 in which the repeating layers contain edge-sharing octahedrally-coordinated PdTe2 chains along the crystallographic b axis. Measurements of electrical resistivity, magnetic susceptibility and specific heat on the Ta4Pd3Te16 crystals, grown via a self-flux method, consistently demonstrate bulk superconductivity at 4.6 K. Further analyses of the data indicate significant electron-electron interaction, which allows electronic Cooper pairing in the present system.Comment: 3 pages, 3 figure